Newsletter EnginSoft Year 9 n°4 -
3
Flash
Virtual Simulation creates more and more interest in diverse
industrial fields and among the young; it is a driving force for
innovation, for employment and creates opportunities for
companies.
It is in this spirit that we are approaching the New Year at
EnginSoft.
We invite our readers to enjoy the articles in this Newsletter
and to contact us with feedback and ideas for collaboration.
With the CAE Poster Award, EnginSoft fosters and promotes
collaborations between industry and universities. At the
International CAE Conference 2012, the Award was presented
for the first time to six outstanding Young Researchers and
businesses for their highly innovative work in the field of
simulation. Many of our guests with whom I spoke at the
Conference shared the enthusiasm for innovative research
and to create new business, to realize visions, to make the
most out of the enormous resources we have available in our
network.
This issue presents contributions on the use of
modeFRONTIER for the optimization of a boomerang shape,
the analysis work performed for a frequency-reconfigurable
microstrip antenna and the Particle Finite Element Method,
PFEM. The latter is an effective numerical technique for
multidisciplinary engineering problems which involve fluidsoil-structure interaction.
Alenia Aermacchi, Politecnico di Torino and the Università
del Salento inform us about ECS System Simulation for
architecture and performance optimization. Further case
studies cover the development work of Lovato Electric, the
Feat Group, the Department of Information Engineering of
University of Pisa as well as the use of the Grapheur
technology for material selection.
While the year turns to an end,
we are building on these
foundations, on the
opportunities and new
activities we have
created together with
our customers and
partners.
Success is possible –
together.
We introduce the RuBeeCOMP, the INTERCER2 and the
“MUSIC” (which stands for: Multi-layer control & cognitive
System to drive metal and plastic production line for Injected
Components) Research Projects.
Our Software Updates feature the latest ANSYS Workbench
14.5 release and SIMPACK, a multi-body simulation tool.
We report from the TechNet Alliance Fall Meeting in Germany,
the Round Table Meeting of companies from Venetia and offer
a comprehensive review of the International CAE Conference
to which EnginSoft had the great pleasure to welcome more
than 700 attendees.
We encourage our readers to download the Conference
Proceedings and to look at the inspiring work of the awarded
young researchers, the six Posters we also highlight in this
Newsletter.
Please stay tuned to the EnginSoft Training Program and
Event Calendar. We hope to welcome many of you to our CAE
courses and events in 2013 and beyond.
EnginSoft and the Editorial Team wish you and your families
a very happy, healthy and a prosperous New Year!
Stefano Odorizzi
Editor in chief
Ing. Stefano Odorizzi
EnginSoft CEO and President
Flash
4 - Newsletter EnginSoft Year 9 n°4
Sommario - Contents
CASE STUDIES
6
10
14
16
24
26
30
33
Optimization of a Boomerang shape using modeFRONTIER
The Particle Finite Element Method. An effective numerical technique for multidisciplinary engineering problems involving
fluid-soil-structure interaction
Frequency-Reconfigurable Microstrip Antenna for Software Defined Radio
ECS System Simulation - Architecture and Performance Optimization from the Early Phases of the System Design
How Geometrical Dimensioning & Tolerancing influence the performances of an electromechanical contactor
Research Activities on Slot-Coupled Patch Antenna Excited by a Square Ring Slot
Grapheur for Material Selection
Studio di fattibilità produttiva attraverso simulazione numerica di processo di forgiatura
RESEARCH & TECHNOLOGY TRANSFER
41
Multidisciplinary Optimization for an IEEE 1902.1 “RuBee” tag integrated in a fiber-reinforced composite structure through the
“RuBeeCOMP” Numerical Platform
44
Meeting conclusivo del progetto "RuBeeCOMP"
SOFTWARE UPDATES
45
47
Le Novità in ambito Mechanical della nuova Release ANSYS Workbench 14.5
Simulating Gear Pairs within SIMPACK
RESEARCH & TECHNOLOGY TRANSFER
50
52
53
EnginSoft coordinates the new “MUSIC” European Project
Modellazione e Progettazione Ottimale di Strutture Ceramiche
EnginSoft ed il progetto INTERCER2
TRAINING
54
Corsi di Addestramento Software 2013
EVENTS
56
58
59
66
68
International CAE Conference: like never before!
70
71
Trainer europei di ANSYS alla scuola EnginSoft
CAE Poster Award. A reward to the genius of young researchers
EnginSoft sostiene le attività di Ricerca dell’Istituto Mario Negri di Milano
Le reti d’impresa? Serve un cambio di mentalità
CAE Conference 2012 welcomed Sponsors from Japan.
Post-conference interviews
Event Calendar
Contents
Newsletter EnginSoft Year 9 n°4 -
5
Newsletter EnginSoft
Year 9 n°4 - Winter 2012
PAGE 16 ECS SYSTEM SIMULATION OF AN
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Contents
Autorizzazione del Tribunale di Trento n° 1353 RS di data 2/4/2008
PAGE 41 MULTIDISCIPLINARY OPTIMIZATION
FOR AN IEE 1902.1 “RUBEE” TAG
ESTECO
www.esteco.com
CONSORZIO TCN
www.consorziotcn.it • www.improve.it
6 - Newsletter EnginSoft Year 9 n°4
Optimization of a Boomerang shape
using modeFRONTIER
A boomerang is a flying object apparently simple but
particularly challenging for the complex physics modeling,
since it should indeed involve:
• six degrees of freedom body dynamics;
• aerodynamics of rotational blades;
• personal capabilities of the thrower;
In this paper we show how the design optimization software
modeFRONTIER, developed by ESTECO, can be employed for a
non-standard problem consisting in the numerical simulation
of the boomerang flight and the final optimization of its
shape.
The boomerang trajectory is obtained by means of a dynamic
model integrated to a CFD analysis able to compute
aerodynamic coefficients. To steer the complete optimization
process modeFRONTIER is coupled to Catia v5 for the
boomerang shape modification, to MATLAB for the dynamic
simulation, and to Star-CCM+ for aerodynamic analysis.
Moreover, dedicated RSM (Response Surfaces Methods)
available in modeFRONTIER are used to extrapolate the
aerodynamic coefficients as a function of the boomerang
angle of incidence and velocity, as required by the dynamic
model, allowing a reduced number of CFD analyses for each
geometric configuration. Different design simulations are
therefore automatically executed by modeFRONTIER,
following a dedicated optimization strategy until the optimal
geometry of the boomerang is found accordingly to the
specified requirements, such as minimum energy for the
launch and desired accuracy in returning.
1. Equations of the boomerang motion
Considering that a boomerang spins fast, it is possible to
write the so-calleds moothed boomerang equations in which
the different quantities (velocities, angles, forces) are timeaveraged over a boomerang rotation:
where: Iz is the maximum boomerang principal moment of
inertia; V is the velocity magnitude of the boomerang center
Case Histories
of mass; m the boomerang mass; ψ is the angle of incidence
of the boomerang; ϑ, φ, ψ are the Euler angles of a xyz
reference system partially fixed on the boomerang (such that
the boomerang center of mass is always placed in the xyz
origin, the z axis is always directed as the maximum
boomerang moment of inertia axis, namely normal to the
section plane shown in Fig.3, and the projection of the
boomerang center of mass velocity on the xy planes is
directed as the –x axis); ωz the boomerang angular velocity
around the z axis; Tx, Ty, Tz, Fx, Fy, Fz, are torque and force
components in the xyz reference system, basically due to the
interaction between the boomerang and the air and the
gravity force. The gravity force can be expressed in the xyz
reference system as:
The absolute position of the boomerang center of mass can
be found as function of the previous parameters by:
The equations of motion can be integrated numerically (high
order Runge-Kutta method) once the initial conditions are
provided and the forces and torques are available at any time
step.
A candidate boomerang trajectory can therefore be simulated
through the flowing steps:
i) for a certain number of Ψ and U pairs (where U=V/ωza),
with a distance between the boomerang center of mass
and the farthest boomerang point from the center of
mass) the corresponding not-dimensional values of F and
T are computed by CFD simulations: a dimensional
analysis can prove indeed that F and T depend only on Ψ
and U for a given boomerang geometry and for a Reynolds
number range typical of boomerang flights;
ii) response surfaces for F(Ψ,U) and T(Ψ,U) are built;
iii) equations of motion are integrated starting from given
initial conditions and using the response surfaces
computed previously to express forces and torques at any
position and time step.
The trajectory of the boomerang is affected by the initial
conditions, namely by the way the boomerang is launched.
Newsletter EnginSoft Year 9 n°4 -
7
Four launching parameters are considered (they will be
automatically tuned for each candidate boomerang by the
optimization methodology described in section 4):
• V: initial boomerang translational velocity;
• Spin: initial boomerang spin;
• Aim: angle between the initial boomerang translational
velocity and the horizontal plane;
• Tilt: angle between the initial boomerang rotational
plane and the vertical axis (0° tilt corresponds to a
vertical boomerang plane of rotation).
2. Boomerang Parameterization
The boomerang geometry chosen for the optimization will be
the classical two arms “V” and “Ω” shape type.
The most important parameters that affect the boomerang
behavior are linked to the blades profile, the angle between
the two arms and the dihedral of the arms. A total number of
9 input parameters has been defined.
A. Blade profiles
Changing the profile by
playing with the angle
of attack and cutting on
the top of the leading
and trailing edge can
change a lot the lift
provided by the arm.
The lift in particular
affects
the
turn
capability
of
the Fig. 1 - Effect on blade profile of Bezier
boomerang (precession control points
effect). The arc blades
are in general designed with a positive angle of attack; this
helps the boomerang plane to lay down and to float in air.
For the parametric boomerang geometry a flat bottom airfoil
has been chosen. The blade profiles are built by a Bezier
parametric curve, with 4 control points.
The profile shape is modified by the changing vertical and
horizontal position of the Bezier control points. In this way
it is possible to change the angle of attack and the thickness
of the blades (see Fig.1).
The profiles of the leading and of the trailing arm are
controlled by the same parameters, in order to reduce their
total number. In particular the vertical position of the
trailing arm is set as a fraction of the vertical position of the
leading arm.
B. Dihedral angle
Boomerang arms usually have a positive dihedral angle of
about 10°-15°; the dihedral affects both the lift and the lay
down velocity of the rotation plane, keeping practically
unchanged the mass of the boomerang.
The boomerang parametric model is provided with the two
parameters α and d that allow to change the dihedral by
removing a small amount of material from the boomerang
arms tips (Fig.2). The α parameter is basically the stabilizer’s
angle of attack.
Fig. 2 - Leading and trailing edges; dihedral angle.
C. Angle between arms
This angle usually ranges between 70° and 140°. In fact, this
parameter has an important effect on the boomerang
stability.
The length of the arms is fixed to keep a constant overall size
of the boomerang.
3. Aerodynamic forces computation details by CFD
The CFD software employed is Star-CCM+.
The approach we considered consists in using two reference
systems - one external and inertial, the other fixed with
respect to the boomerang and having its origin placed in the
boomerang center of mass. Also, two domains and two grids
are used: the first is spherical, having its origin placed in the
boomerang center of mass and associated to the boomerang
reference system; the second corresponds to an external
parallelepiped shape associated to the external reference
system.
The internal spherical domain is provided with a rotation
velocity around an axis normal to the boomerang plane and
passing through the boomerang center of mass. The
information exchange between the two domains is provided
by an interface boundary that allows to interpolate the field
values.
In Star-CCM+, a polyhedral mesh with prisms layers at the
boomerang walls is defined within the sphere around the
boomerang and an hexahedral mesh is defined in the rest of
the domain (Fig.3). The two-equations RANS SST (Shear
Stress Transport) turbulent model, with wall functions, is
chosen
and
a
segregated solver with
constant density is
employed. A mesh size
of about 2.5 millions
of cells has been
defined, this being a
good tradeoff between Fig. 3 - Particular of a mesh section
Case Histories
8 - Newsletter EnginSoft Year 9 n°4
Fig. 4 - CFD results on different revolution frames
accuracy and computational efforts. Fig.4 shows the pressure
field on a boomerang surface in different time steps during a
rotation. It is possible to notice that the pressure force on
each arm changes a lot during the rotation according to the
relative position of the blades with respect to the
translational velocity. At the end of the numeric simulation
(for a given Ψ,U pair) the averaged forces and torques acting
during the rotation are computed and then the corresponding
F and T are available.
4. Process flow automation in modeFRONTIER
The whole process aiming at evaluating and optimizing the
performances of the boomerang has been completely
automatized through the software modeFRONTIER.
In this modular environment, the complete process flow is
defined by the user, who can select among several available
optimization algorithms, including Genetic and Evolutionary
Algorithms, Game Strategies, Gradient-based Methodologies,
Meta-Models and Robust Design Optimization.
Fig. 5 - modeFRONTIER main workflow
modeFRONTIER effectively automates the computation of the
boomerang trajectory through the following steps:
1. modify the boomerang Catia model parameters;
2. obtain the updated geometry (stl file) from Catia and
transfer it to Star-CCM+ execution module;
3. launch Star-CCM+ to build the computational mesh;
4. launch different Star-CCM+ simulations using the same
mesh prepared as above varying U and Ψ parameters for
an appropriate number of samples; for each U and Ψ pair
the corresponding forces and torques F and T are
obtained;
Case Histories
5. use the set of simulations computed in iv) as training set
to build in modeFRONTIER response surfaces to obtain
F(Ψ,U) and T(Ψ,U) over the whole range of variation of
Ψ,U
6. pass the response surfaces and the boomerang inertia
data to a MATLAB script to compute the trajectory by
integrating equations of motion using a 4th order RungeKutta method;
7. run an internal optimization for the given configuration
to tune the four launching parameters (by minimizing the
arrival distance);
8. the main multi-objective algorithm assesses how good
the trajectory is with respect to specified objectives
(total energy needed for the launch to be minimized)
9. the steps i)-viii) are repeated automatically by the
algorithm until one or more optimal configurations are
obtained.
The modeFRONTIER workflow is shown in Fig.5. In particular,
on the top we find the nodes (green subsystem) that define
the range of variations of all the geometrical parameters,
then the process flow (black line) starts with the interfaces
to select the optimization algorithms and set their options,
to continue with the CATIA direct interface that allows to
automatically update the geometric model at the variation of
the parameters, obtaining as results the updated Stl model,
which is transferred to the following script node used to run
Star-CCM+ to create the mesh for the proposed geometry.
The mesh (.sim file) is then transferred to the following
application node, which basically launches in batch mode
another modeFRONTIER project file, running a set of CFD
computations through Star-CCM+ on the same mesh varying
U and Ψ parameters, as described at point iv) above.
The output of the internal
modeFRONTIER project is a
Response Surface (RSM) or Metamodel, based on the available
training set, able to extrapolate
F(Ψ,U) and T(Ψ,U) over the whole
range of variation of the two
parameters (fig.6). The algorithm
used for the RSM training is Kriging
and the model is automatically
exported as a C-script, which can be
read by MATLAB.
The last application node in the
process flow is another modeFRONTIER project node, called
“launch_parameters_tuning”. This node actually runs another
optimization project in batch mode, using as input variables
the four launch parameters described in section 1. The
boomerang shape is fixed and the objective is defined by the
minimization of the distance from the arrival position and
the launching position. For this purpose, a fast monoobjective algorithm is used (Simplex) and the project just
executes a MATLAB script through the corresponding direct
interface for each set of launching parameters; basically the
script drives a Runge-Kutta integration to compute the
Newsletter EnginSoft Year 9 n°4 -
Fig. 6 - Response surfaces of boomerang aerodynamic forces
boomerang trajectory (retrieving the needed F(Ψ,U) and
T(Ψ,U) values for each integration time step directly from
the Response surface available for each boomerang
geometry).
The final outcome of the modeFRONTIER Batch node in the
main process flow for each boomerang geometry is therefore
its tuned trajectory, whose performances are to be optimized
in the external loop. For this purpose, from this node the
following outputs are extracted:
• Range: this is the maximum distance reached by the
boomerang during its flight; it has just been considered
as a constraint in the optimization, to penalize
configurations of too small range;;
• Accuracy: this is the difference between the position
from which the boomerang is launched and the position
where the boomerang returns (optimized by the internal
loop as described above for each boomerang candidate
solution)
• Energy: this is the energy (translational plus rotational)
necessary to launch the boomerang, that is a quantity to
be minimized (to reduce the effort for the thrower).
5. Optimization Strategy and Optimization Results
Several tests were performed in order to find the proper
number of simulations required to create enough accurate
response surfaces. It has been found that a matrix of 12
points guarantees an error of approximation lower than 5%
and this was the size of the training set finally selected. This
means that each boomerang trajectory computation needs 12
CFD simulations. For this reason a classical multi-objective
optimization algorithm that may require hundreds of designs
evaluations is not practically feasible, therefore a different
strategy, based on the Game Theory (Hierarchical Games), has
been chosen.
As indicated in the previous chapter, two different objectives
(returning accuracy and launch global energy) have to be
considered. Actually, any candidate solution is first
optimized by the internal workflow in order to tune the
launching parameters (follower player); then, the identified
optimal solution is evaluated by the external optimization
workflow which handles the energy objective minimization
by changing properly the geometrical parameters (leader
player). Note that for both the internal and external
optimizer the same modeFRONTIER algorithm, Simplex, has
9
been used due to its efficiency to solve single-objective
problems in few iterations.
Fig.7 reports the global results of the optimization process,
in the space of the objectives and constraints considered. In
particular the abscissa reports the launch energy (Joule), the
ordinate indicates the range (meters), and the color of the
bubbles reports the returning accuracy for each design
(distance in meters).
At the end of the process, one of the optimal boomerang
configuration has been chosen and its geometry and
trajectory are also reproduced in Fig.8. The energy required
to launch the boomerang is 3.5 J, the ratio of rotational with
total energy is only 7% that corresponds to an initial spin of
about 4 Hz and to an initial translational velocity equal to 15
m/s; the tilt angle is 0°, while the aim is about 20°. This set
should make the boomerang launch pretty easy, with a range
of 14.5 m.
In conclusion, this paper has described an automatic and
efficient methodology for the multi-objective optimization of
a boomerang shape, resulting an interesting benchmark and
proof of concept to illustrate the multi-objective and multidisciplinary capabilities of the optimization environment
modeFRONTIER.
Rosario Russo, Alberto Clarich - ESTECO Spa
Enrico Nobile, Carlo Poloni - Università di Trieste
For more information:
Francesco Franchini, EnginSoft
[email protected]
Fig. 7 - Optimization results
Fig. 8 - Optimal boomerang configuration and trajectory
Case Histories
10 - Newsletter EnginSoft Year 9 n°4
The Particle Finite Element Method.
An effective numerical technique for
multidisciplinary engineering problems
involving fluid-soil-structure interaction
Introduction
The analysis of problems involving the interaction of fluids,
soil/rocks and structures is relevant in many areas of
engineering. Examples are common in the study of landslides
and their effect on reservoirs and adjacent structures, off-shore
and harbour structures under large waves, constructions hit by
floods and tsunamis, soil erosion and stability of rockfill dams
in overspill situations, excavation and drilling problems in civil
and petroleum engineering, etc.
The author and his group have developed in previous works a
particular class of Lagrangian formulation for solving problems
involving complex interactions between (free surface) fluids and
solids. The so-called particle finite element method (PFEM,
www.cimne.com/pfem), treats the mesh nodes in the fluid and
solid domains as particles which can freely move and even
separate from the main fluid domain representing, for instance,
the effect of water drops. A mesh connects the nodes
discretizing the domain where the governing equations are
solved using a stabilized FEM.
An advantage of the Lagrangian formulation used in PFEM is that
the non-linear and non symmetric convective terms disappear
from the fluid equations. The difficulty is however transferred to
the problem of adequately (and efficiently) moving the mesh
nodes. In the next section the key ideas of the PFEM are
outlined. Next the basic equations for a general continuum using
a Lagrangian description and the formulation are schematically
presented. We present several examples of application of the
PFEM to solve multidisciplinary FSSI problems such as the
motion of rocks by water streams, the stability of breakwaters
and constructions under sea waves, the study of a landslide
falling into a reservoir, the sinking of ships and the collision of
ships with ice blocks.
Case Histories
The basis of the particle finite element method
In the PFEM both the fluid and the solid domains are modelled
using an updated Lagrangian formulation. That is, all variables
are assumed to be known in the current configuration at time t.
The new set of variables in both domains is sought for in the
next or updated configuration at time t + Δt. The finite element
method (FEM) is used to solve the equations of continuum
mechanics for each of the subdomains. Hence a mesh
discretizing these domains must be generated in order to solve
the governing equations for each subdomain in the standard FEM
fashion. The quality of the numerical solution depends on the
discretization chosen as in the standard FEM. Adaptive mesh
refinement techniques can be used to improve the solution.
Fig. 1 - Scheme of a typical solution with PFEM. Sequence of steps for
moving a “cloud” of nodes representing a domain containing a fluid and a
solid part from time n (t=tn) to time n+2 (t=tn + 2Δt)
Newsletter EnginSoft Year 9 n°4 -
For clarity purposes we will define the collection or cloud of
nodes (C) pertaining to the analysis domain (V) containing the
fluid and solid subdomains and the mesh (M) discretizing both
domains.
A typical solution with the PFEM involves the following steps.
1. The starting point at each time step is the cloud of points
in the fluid and solid domains. For instance nC denotes the
cloud at time t = tn (Figure 1).
2. Identify the boundaries for both the fluid and solid domains
defining the analysis domain nV in the fluid and the solid.
This is an essential step as some boundaries (such as the
free surface in fluids) may be severely distorted during the
solution, including separation and reentering of nodes. The
Alpha Shape method is used for the boundary definition.
3. Discretize the fluid and solid domains with a finite element
mesh. nM We use an effect mesh generation scheme based on
the extended Delaunay tesselation.
4. Solve the coupled Lagrangian equations of motion for the
overall continuum. Compute the state variables in at the
next (updated) configuration for t + Δt: velocities, pressure
and viscous stresses in the fluid and displacements, stresses
and strains in the solid.
5. Move the mesh nodes to a new position n n+1C where n+1
denotes the time tn + Δt, in terms of the time increment
size. This step is typically a consequence of the solution
process of step 4.
6. Go back to step 1 and repeat the solution for the next time
step to obtain n+2C (Figure 1).
We emphasize that the key differences between the PFEM and
the classical FEM are the remeshing technique and the
identification of the domain boundary at each time step.
Generation of a new mesh
A key point for the success of the PFEM is the fast regeneration
of a mesh at every time step on the basis of the position of the
nodes in the space domain. In our work the mesh is generated
using the so-called extended Delaunay tesselation (EDT). As a
general rule for large 3D problems meshing consumes around
15% of the total CPU time per time step, while the solution of
Fig. 2 - Modelling of contact conditions at a solid-solid interface with
the PFEM
11
the equations (with typically 3 iterations per time step) and the
system assembly consume approximately 70% and 15% of the
CPU time per time step, respectively. These figures refer to
analyses in a single processor Pentium IV PC and prove that the
generation of the mesh has an acceptable cost in the PFEM.
Indeed considerable speed can be gained using parallel
computing techniques.
Identification of boundary surfaces
One of the main tasks in the PFEM is the correct definition of
the boundary domain. Boundary nodes are sometimes explicitly
identified. In other cases, the total set of nodes is the only
information available and the algorithm must recognize the
boundary nodes (Figure 2).
In our work we use a Delaunay partition for recognizing
boundary nodes and, hence, boundary surfaces. This is
performed by using the so-called Alpha Shape method.
This method also allows one to identify isolated fluid particles
outside the main fluid domain. These particles are treated as
part of the external boundary where the pressure is fixed to the
atmospheric value. We recall that each particle is a material
point characterized by the density of the solid or fluid domain
to which it belongs. The mass lost when a boundary element is
eliminated due to departure of a node from the analysis domain
containing a fluid is regained when the node falls down and a
new boundary element is created by the Alpha Shape algorithm.
The boundary recognition method is useful for detecting contact
conditions between the fluid domain and a boundary, as well as
between different solids as detailed in the next section.
Treatment of contact conditions in the PFEM
Known velocities at boundaries in the PFEM are prescribed in
strong form to the boundary nodes. These nodes might belong
to fixed external boundaries or to moving boundaries.
Contact between fluid particles and fixed boundaries is
accounted for by the incompressibility condition which naturally
prevents fluid nodes to penetrate into the solid boundaries.
The contact between two solid interfaces is treated by
introducing a layer of contact elements between the two
interacting solid interfaces. This layer is automatically created
during the mesh generation step by prescribing a minimum
distance (hc) between two solid boundaries. If the distance
exceeds the minimum value (hc) then the generated elements
are treated as fluid elements. Otherwise the elements are treated
as contact elements where a relationship between the tangential
and normal forces and the corresponding displacement is
introduced (Figure 2).
This algorithm allows us to identify and model complex
frictional contact conditions between two or more interacting
bodies moving in water in an extremely simple manner. The
algorithm can also be used effectively to model frictional
contact conditions between rigid or elastic solids in structural
mechanics applications.
Modeling of bed erosion
Prediction of bed erosion and sediment transport in open
channel flows are important tasks in river and environmental
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12 - Newsletter EnginSoft Year 9 n°4
engineering. Bed erosion can lead to instabilities of the river
basin slopes. It can also undermine the foundation of bridge
piles thereby favouring structural failure.
Modeling of bed erosion is also relevant for predicting the
evolution of surface material dragged in earth dams in overspill
situations. Bed erosion is one of the main causes of
environmental damage in floods.
In a recent work we have proposed an extension of the PFEM to
model bed erosion. The erosion model is based on detaching
elements belonging to the bed surface in terms of the frictional
work at the surface originated by the shear stresses in the fluid.
The resulting erosion model resembles Archard law typically used
for modeling abrasive wear in surfaces under frictional contact
conditions.
Sediment deposition can be modeled by an inverse process.
Hence, a suspended node adjacent to the bed surface with a
velocity below a threshold value is attached to the bed surface.
Fig. 5 - Erosion of a soil mass due to sea waves and the subsequent falling
into the sea of an adjacent lorry
Fig. 6 - Simulation of landslide falling on constructions using PFEM
Fig. 3 - Breaking waves on breakwater slopes containing reinforced
concrete blocks
Examples
Impact of sea waves on piers and breakwaters
Figure 3 shows the analysis of the effect of breaking waves on
two different sites of a breakwater containing reinforced
concrete blocks (each one of 4x4x4 mts). The figures correspond
to the study of Langosteira harbour in A Coruña, Spain using
PFEM.
Soil erosion problems
Figure 4a shows the capacity of the PFEM for modelling soil
erosion, sediment transport and material deposition in a river
bed. The soil particles are first detached from the bed surface
under the action of the jet stream. Then they are transported by
the flow and eventually fall down due to gravity forces into the
bed surface at a downstream point.
Figure 4b shows the progressive erosion of the unprotected part
of a breakwater slope in the Langosteira harbour in A Coruña,
Spain. The non protected upper shoulder zone is progressively
eroded under the sea waves.
Falling of a lorry into the sea by erosion of the road
slope due to sea waves
Figure 5 shows a representative example of the progressive
Fig. 4 - (a) Erosion, transport and deposition of soil particles at a river bed
due to an impacting jet stream (b) Erosion of an unprotected shoulder of a
breakwater due to sea waves
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Fig. 7 - Lituya Bay landslide. Left: Geometry for the simulation. Right:
Landslide direction and maximum wave level
erosion of a soil mass adjacent to the shore due to sea waves
and the subsequent falling into the sea of a 2D object
representing the section of a lorry. The object has been modeled
as a rigid solid. This example and the previous ones, although
still quite simple and schematic, show the possibilities of the
Fig. 8 - Lituya Bay landslide. Evolution of the landslide into the reservoir
obtained with the PFEM. Maximum level of generated wave (551 mts) in the
north slope
Newsletter EnginSoft Year 9 n°4 -
13
height observed was 208 mts, while the PFEM result (not shown
here) was 195 mts (6% error).
Simulation of sinking of ships
The PFEM can be effectively applied for simulating the sinking
of ships under a variety of scenarios. Figure 9 shows images of
the 2D simulation of the sinking of a cargo vessel induced by a
breach in the bow region. Figure 10 displays a 3D simulation of
the skinking of a simple fisherman boat induced by a hole in the
side of the hull. These examples evidence the potential of PFEM
for the study of the sinking of ships.
Colision of boat with ice blocks
Figures 11 shows an example of the application of PFEM to the
study of the collision of a ship with floating ice blocks.
The boat and the ice blocks have been modelled as rigid bodies
in this example. Indeed, the deformation of the ship structure
due to the ice-ship interaction forces can be accounted for in
the analysis.
Fig. 9 - 2D simulation of the sinking of a cargo vessel due to a breach in the
bow region. (a) Water streamline at different times. (b) Water velocity
pattern at different times during sinking
PFEM for modeling complex FSSI problems involving soil erosion,
free surface waves and rigid/deformable structures.
Conclusions
The particle finite element method (PFEM) is a promising
numerical technique for solving fluid-soil-structure interaction
(FSSI) problems involving large motion of fluid and solid
particles, surface waves, water splashing, frictional contact
situations between fluid-solid and solid-solid interfaces and bed
erosion, among other complex phenomena. The success of the
PFEM lies in the accurate and efficient solution of the equations
of an incompressible continuum using an updated Lagrangian
formulation and a stabilized finite element method allowing the
use of low order elements with equal order interpolation for all
the variables. Other essential solution ingredients are the
efficient regeneration of the finite element mesh, the
identification of the boundary nodes using the Alpha-Shape
technique and the simple algorithm to treat frictional contact
conditions and erosion/wear at fluid-solid and solid-solid
interfaces via mesh generation. The examples presented have
shown the potential of the PFEM for solving a wide class of
practical FSSI problems in engineering.
Modelling of landslides
The PFEM is particularly suited for modelling landslide motion
and its interaction with structures and the environment.
Figure 6 shows a simulation using PFEM of a soil mass
representing a landslide falling on four constructions modelled
as rigid body solids. A case of much interest is when a landslide
occurs in the vicinity of a reservoir. The fall of debris material
into the reservoir typically induces large waves that can overtop
the dam originating an unexpected flooding that can cause
severe damage to the constructions and population in the
downstream area. We present some results of the 3D analysis of
the landslide produced in Lituya Bay (Alaska) on July 9th 1958
(Figure 7). The landslide was originated by an earthquake and
Eugenio Oñate
mobilized 90 millions tons of rocks that fell on the bay
International Center for Numerical Methods
originating a large wave that reached a hight on the opposed
in Engineering (CIMNE), Spain
slope of 524 mts. Figure 8 shows images of the simulation of the
Universitat Politècnica de Catalunya (UPC), Spain
Lituya Bay landslide with PFEM.
PFEM results have been compared
with observed values of the
maximum water level in the north
hill adjacent to the reservoir. The
maximum water level in this hill
obtained with PFEM was 551 mts. Fig. 10 - 3D simulation of the sinking of a boat induced by a hole in the side of the hull
This is 5% higher than the value
of
524
mts.
observed
experimentally. The maximum
height location differs in 300 mts
from the observed value. In the
south slope the maximum water Fig. 11 - 3D simulation of a boat colliding with five ice blocks
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14 - Newsletter EnginSoft Year 9 n°4
Frequency-Reconfigurable
Microstrip Antenna for
Software-Defined Radio
The increasing demand for portable devices with wireless
connectivity within a wide frequency spectrum presents an
ambitious challenge for the designer of the RF front-end who
has to manage different wireless standards (GSM, UMTS,
WiMAX, WiFi, Bluetooth, LTE). Covering several frequency
bands simultaneously with a single antenna can be a very
demanding task, which is why the employment of many
different antennas integrated in the device and the use of
multiband or broadband antennas might be a feasible solution
for the problem. The use of different antennas implies an
increase of the overall cost and space requirements.
Broadband antennas transmit and receive signals within a
large bandwidth but they may suffer an unbearable
deterioration of the signal to noise ratio and thus a reduction
of the overall efficiency of the system. Moreover, the
electromagnetic spectrum is a shared resource that is more
and more congested with the increasing number of users of
wireless devices and the further exploitation of the available
frequencies by other services poses practical and regulatory
difficulties. To cope with this problem, the employment of an
unused part of the spectrum or the opportunistic and
temporary use of a shared portion may offer new resources.
upgrade, without changing the controlled hardware. This
ambitious objective imposes strict requirements to the
capabilities of the device radio front-end especially in terms of
the requested frequency agility necessary for the smart and
dynamic adaptation to the wireless environment. In particular,
severe constraints are placed on critical components such as
filters, matching networks and antennas.
The SDR architecture requires a reconfigurable antenna which
is able to modify one, or a combination, of its fundamental
radiation properties depending on the adopted scheme [6]. A
radiating device can exhibit a frequency agility, which allows
to set its instant working frequency, a change in pattern
shape, or an alteration of the electric field polarization. The
reconfiguration is obtained by adjusting the path of currents
on the antenna or even by altering the geometry of the
radiating device. The three aforementioned degrees of
reconfigurability can be realized by recurring to different
technologies among which electrical RF switches such as PIN
diodes and varactors, photoconductive elements or MEMS.
Different kinds of antennas have been proposed for the
enhancement of the SDR radio frontend including PIFAs,
monopoles and patches.
The Cognitive Radio (CR) concept has been proposed as a
Within this framework, we have recently developed a
solution since the related CR radio network is able to evaluate
reconfigurable microstrip patch antenna by using PIN diodes
the instant occupancy of spectrum and decides on this basis
as RF switches whose biasing network is
how to allocate services on temporarily
software-controlled
via
a
PIC
unoccupied parts of the EM spectrum.
microcontroller. The microstrip patch
This recent paradigm of communication
antenna has been chosen for its low
allows an efficient spectrum usage but
profile,
robustness
and
easy
also poses some challenges, with regard
manufacturing. The aim is to obtain an
to hardware and software, which have
antenna with a reconfigurable
motivated the rise of the Software
frequency response between 850 MHz
Defined Radio (SDR) concept during the
and 3.5 GHz by simply changing the
last years. A device based on SDR is an
state of the RF switches. After a
integrated system which must exhibit
preliminary optimization study based on
extreme hardware performance to
the cavity model of the patch antenna,
support the necessary software-based
we have considered the configuration
signal processing and guarantee the
shown in Fig. 1 in which five PIN diodes
desired flexibility. The final goal is Fig. 1 - Top view of the frequency-reconfigurable
microstrip patch antenna. The continuous circles
are able to guarantee a proper sweep of
therefore to implement most of the radio indicate group#1 whereas dashed circles designate
the working frequency. The positions of
system in software, easy to update or group#2.
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Newsletter EnginSoft Year 9 n°4 -
the RF switches have been chosen by inspecting the path of
the currents on the patch surface to individuate the most
suitable placement of the diodes to guarantee the current
flow. The overall size of the patch antenna is 84 mm × 70 mm.
It is worthwhile to mention that the size of each element in
the antenna and the position of the PIN diodes were chosen
under two imposed constraints. First of all, in order to reduce
the complexity of the design, we aimed at a configuration
where all the RF-switch biasing lines had to be placed on the
top layer of the antenna substrate, avoiding any cut in the
ground plane. Next, we also searched for a solution without
any matching network thus requiring in each RF-switch state
an impedance close to the 50 Ohm of the feeding line. Two
shorting pins with a 1.0-mm-diameter were inserted as
illustrated in Fig. 1, the former in one of the outer sections
and the latter in the inner element.
To obtain a correct evaluation of the antenna behavior, the
diodes have been considered by using their circuit model in
the Ansoft HFSS simulations (Fig. 2) instead of substituting
them as an open circuit in the "Off"
case and as a short circuit when in
"On" state. The employed PIN diode
is an Avago HSMP-4890 which
presents Rs = 2.5 Ohm, L = 1 nH, CT
= 0.3 pF and RP in the order of
KOhm. The PIN diodes were placed
by using silver conductive epoxy to
avoid overheating of the device.
Fig. 2 - PIN diode circuit
In our design the five PIN diodes model for the "On" state (a)
have been divided into two groups and "Off" state (b).
(continuous and dashed circles as
shown in Fig.1) thus providing four possible configurations.
Each group allows current to flow when the diodes are in "On"
state whereas the propagation of the RF signal is interrupted
when they are set to "Off" state.
The biasing network comprises two lines on the top of the
dielectric substrate which connect each of the outer sections
of the patch to the DC source. A RF block is necessary to
isolate the RF and DC source on these biasing lines. Moreover,
the inner element of the antenna and the other one inside the
simil-loop element are connected to the ground plane by
using the 1.0-mm-diameter via. This configuration allows
modifying the state of the two RF-switch groups by simply
changing the voltage between the ground plane and the two
lines connected to each
antenna side. In order to
change on demand the
instantaneous frequency,
we have programmed a
PIC16F688
flash
microcontroller to switch
among the four possible
configurations described
above and we have Fig. 3 - The antenna configuration is
completely software-controlled by using the
directly connected the PC which operates on the PIC microcontroller
prototype board to a to change the state of PIN diodes.
15
Fig. 4 - Frequency response of the antenna when PIN diodes belonging to
group#2 are in "On" state and others are in "Off" state.
laptop through an USB interface (Fig. 3). Therefore the
activation and deactivation of the RF switches is performed by
a microcontroller which can change the working frequency on
the basis of the information collected by another antenna
(sensing antenna) which is scouting the available frequency
slots, as proposed in the CR paradigm.
A comparison between the simulated and measured S11
parameters for the configuration with group#1 in OFF state
and group#2 in ON state is reported in Fig.4 and the
agreement is satisfactory except for some frequency shifts
which could be attributed to discrete component tolerances
and soldering effects.
Fig. 5 - Comparison between the simulated (continuous line) and measured
(dashed line with triangles) radiation patterns at 850 MHz: φ = 0 deg., φ =
90 deg.
The simulated and measured patterns on the xz (φ = 0) and yz
(φ = 90) planes are reported in Fig. 5. From the inspection of
the results it is apparent that there is no significant distortion
of the antenna pattern caused by the PIC microcontroller and
the biasing lines.
Ing. Simone Genovesi, Prof. Agostino Monorchio
Microwave and Radiation Lab., Dip. Ingegneria
dell'Informazione (www.mrlab.it)
Università di Pisa
For more information, please contact:
[email protected]
[email protected]
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16 - Newsletter EnginSoft Year 9 n°4
ECS System Simulation - Architecture
and Performance Optimization from
the Early Phases of the System Design
In today’s aircraft thermal design, we can observe a trend
towards electronics systems integration characterized by
higher heat densities and a more frequent use of composite
primary structures. All these factors require robust thermal
management and thermal architecture design already at the
preliminary design stages. The thermal architecture will have
to be developed in order to mitigate thermal risks for
temperature-sensitive equipment as well as to limit the
aircraft systems overdesign. The improvement and
optimization of the thermal architecture is regarded as one of
the key success factors for future aircraft developments. It
requires a complete pyramid of simulation tasks to be set up,
from the individual equipment to aircraft section simulation,
to the global aircraft thermal analysis. Many difficulties arise
from this simulation framework due to the variety of physical
models, partners, techniques and tools used at each level of
the pyramid.
In this context, the aim of this paper is to describe an
Environmental Control System design approach as applied in
Alenia Aermacchi.
The main technical challenges addressed in this paper are:
• Air conditioning pack architecture design
• Air distribution line design and trade-off study,
• Multidisciplinary optimization of the air distribution
system components
• A/C cabin thermal environment evaluation and occupants’
thermal comfort.
Background
The air conditioning system is designed in such a way that it
maintains the air within the pressurized fuselage
Fig. 2 - Thermal aircraft schematic
Fig. 1 - A/C air conditioning pack and air distribution system
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Table 1 - Electrical equipment dissipated power
Newsletter EnginSoft Year 9 n°4 -
compartment at the required level of pressure, temperature,
flow rate and purity.
The air is supplied to the system from the engine compressor,
the hot compressed air is cooled and conditioned in the air
conditioning pack before being distributed to the various
compartments through the air conditioning system (see
Figure 1).
17
As shown in Figure 4, the standard air condition pack
architecture has been considered.
Figure 4 illustrates also the mono-dimensional model built in
LMS Amesim. The heat exchanger mono-dimensional model
(low fidelity model) has been validated by comparing its
results with CFD model results (high fidelity model). In Figure
5, we can see the validation analysis results.
Accordingly, in order to guarantee a
comfortable A/C cabin environment, it is
necessary to design and optimize the air
conditioning pack and air distribution
system.
Air conditioning pack architecture design
Requirements
This study focuses on the following
requirements:
• A/C schematic configuration (see Figure).
• Thermo-acoustic insulation U factor.
• Electrical equipment dissipated power
(see Table 1).
• Temperature requirements for cabin/
cockpit.
• Environmental envelope (see Figure 3).
• The certification and performance
requirements of ECS are reported below:
o Minimum fresh flow per passenger:
0.55 lb/min.
o Minimum fresh flow per crew
member: 10 cfm.
o Minimum fresh flow per galley 15
cfm.
o Maximum ratio recirculation / total
flow 0.4.
o Maximum fresh flow per
passenger/crew member for single
pack operations 0.4.
o Cabin stabilized temperature
between 21°C -27°C.
o Cockpit stabilized temperature
between 21°C-27°C.
Methodology
The design of the air conditioning pack
architecture has been reached through the
following steps:
• Definition of air conditioning pack monodimensional model.
• Definition and validation of heat
exchanger mono-dimensional model.
• Definition of A/C cabin thermal monodimensional model.
• Optimization of heat exchanger design, in
order to meet certification and
performance requirements.
Fig. 3 - Environmental envelope
Fig. 4 - ECS pack 1D- model
Fig. 5 - Heat exchanger size
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18 - Newsletter EnginSoft Year 9 n°4
• Steady state, cruise cold day (40 kft, -70
°C, Mach 0.85, 20% passengers)
The heat exchanger has been defined in terms
of its geometrical characteristics and number
of plates.
As shown in Figure 7, the analysis results
confirm the compliance of the air
conditioning pack architecture with the
certification and performance requirements.
Fig. 6 - A/C mono-dimensional thermal model
Air distribution line design and
trade-off study
In order to determine the air conditioning
pack architecture, the second step focused on
the definition of the air distribution system.
The latter depends on the following aspects:
• Performance in terms of pressure losses.
• Integration in aircraft.
• Reliability and maintainability.
Two different architectures have been analyzed.
The first one (Architecture A) shown in Figure 8 is a parallel
architecture composed of an underfloor line and a low
pressure air distribution line that allow to distribute the
airflow coming from the mixing chamber in parallel through
the risers.
Fig. 7 - Performance of air
conditioning pack
Fig. 8 - Air distribution system CAD model – Architecture A
Fig. 10 - Mono-dimensional model Architecture A.
Fig. 9 - Air distribution system CAD model – Architecture B
In order to design the air cycle machine and heat exchanger,
the cabin aircraft mono-dimensional thermal model shown in
Figure 6 has been built. It allowed to evaluate the cabin
thermal environment and hence the compliance with varying
pack performance depending on the heat exchanger design.
The operating conditions analysed have been:
• Steady state, ground hot day (ISA+25, 100% passengers)
• Steady state, ground cold day (ISA-55, 20% passengers)
• Steady state, cruise hot day (40 kft, -35°C, Mach 0.85,
100% passengers)
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Fig. 11 - Mono-dimensional modelArchitecture B.
Newsletter EnginSoft Year 9 n°4 -
19
As boundary conditions we assumed the data reported below
in various flight conditions, then the steady state analysis
has been carried out:
• Temperature, air flow, pressure and humidity coming from
the air conditioning pack.
• External conditions in terms of temperature.
• Equipment and light heat load.
• Passengers heat load.
Figure 12 shows the analysis results in terms of pressure drop
vs mass flow curve. In particular, the results highlight that
the air distribution system pressure losses of Architecture A
are higher than those of Architecture B.
Fig. 12 - Pressure loss vs massflow curves
The second one (Architecture B) shown in Figure 9 is a
sequential architecture where the under floor is much limited,
and the cabin air distribution system is developed above the
floor.
Starting from the CAD model shown above, a monodimensional model for each architecture has been built in LMS
Amesim (see Figures 10 and 11). The mono-dimensional
models are composed of the following parts:
• Connection with air conditioning pack mono-dimensional
model.
• Cockpit line
• Cabin line
• Simplified A/C thermal model as thermal node.
• Internal macro that allows to simulate the physiology of
the passengers in terms of heat load and humidity
released.
Fig. 13 - Technical performance measure
A comparison analysis has been performed by means of a
Technical Performance Measure (TPM) methodology.
First, all of the key requirements (performance, system
integration in the aircraft, RMT) have been defined,
categorized and weighted according to their degree of
importance. Key factors and preferences have been
established on the basis of Alenia’s experiences.
Normalized weights of 0-1 range have been assigned as per
the above to each key requirement.
Then, each requirement has been split into sub-requirements,
as follows:
• Performance:
o Pressure loss.
• System Integration in the aircraft:
o Influence on cabin noise;
o Weight;
o Ease of installation.
• RMT
o Reliability;
o Maintainability.
Each sub-requirement has been weighted according to its
degree of importance compared to the others. Then, each
weight has been normalized in absolute terms, in accordance
with the key requirements.
Also a score has been assigned to each sub-requirement, as
follows:
• 1 = VERY POOR: the proposed solution does not meet the
system’s requirements;
• 2 = POOR: the proposed solution does not meet the
system’s requirements but the requirement deviation is
acceptable;
Fig. 14 - CAD model for Outlet
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20 - Newsletter EnginSoft Year 9 n°4
Fig. 15 - Parametric model
• 3 = ACCEPTABLE: the proposed solution meets the system’s
requirements, but with some risks.
• 4= GOOD: the proposed solution meets the system’s
requirements.
Subsequently, attributes, weights and scores have been
allocated, the quantitative frame which builds a rational
evaluation has been defined, calculating the relevant
weighted score for each sub-requirement.
Figure 13 shows details of the TPM comparison analysis
results.
Following the outcome of the TPM approach, the results of
architecture A of the air distribution system are preferred.
Multidisciplinary optimization of air distribution system
components
The shape optimization of the air vent outlet has been carried
out through the following phases:
1. Mesh accuracy study
2. Input sensitivity study
3. Design of Experiment (DOE) Analysis
4. Optimization
5. Automatic updating of the party in the product
Design specifications
Based on the flow of incoming air assigned to the maximum
operative mass flow rate, the shape of the air vent outlet has
been optimized (Figure 14) with the objective of minimizing
pressure losses and noise levels. To achieve these goals, the
geometry for the surface connection between the inlet and
outlet of the nozzle has been parameterized.
Among the geometric parameters that
were evaluated for the optimization is
the angle Alpha; it is important to
mention that this angle is formed by
the axis coming from the centre of the
inlet and the centre of the outlet, it
changes the direction in which the air
flow enters the cabin.
Parameterization
For the parameterization 6 points have been identified; these
6 points are located on the intersection of a virtual plane
perpendicular to the line joining the centres of the inlet and
the exit outlet. The 6 splines in Figure 15 have been initially
identified as points A, B, C, D, E, F. As these point change
their locations, the area of the opening will be adapted for
the purpose of the optimization. Based on this configuration
and by changing the location of the points, it becomes
possible to update the area of the opening and in this way to
modify the purpose of the optimization.
modeFRONTIER Model
In the modeFRONTIER model the geometric inputs are held
constant while varying only the parametric data for the CAE
model.
The process flow consists of three blocks:
1. CATIA process: it opens the file CatiaV5 CATPart geometry
of the nozzle, then it converts files into IGS and sends
them to the next process.
2. STAR Process: StarCCM+ runs a mesh with Base Size Length
which is assigned to the CAE_Input, then it automatically
performs the calculations. It estimates the time taken
(CPU_Time), and sends the simulation file (SIMfile) for
the next process.
3. Process PostPRO: StarCCM+ checks for the simulation file,
and if there are further calculations to determine the
pressure and noise levels, in particular, according to the
PostPRO_Input, a visual representation is saved in a jpeg
file containing the pressure, the speed or noise level, as
well as images of the mesh and the graph of the residue.
The variables monitored are CPU
processing time in seconds, CPU_Time, and
total pressures in Pascal in and out of the
nozzle: p_in p_out respectively.
Fig. 16 - modeFRONTIER model for shape and noise optimization of the outlets
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Design Of Experiment (DOE) Analysis
In modeFRONTIER (whose workflow is
shown in Figure 16) a DOE analysis has
been performed taking into account the 3
free parameters dx_CF, dy_AB, and dy_DE,
while, dx_AB, dx_DE, and dy_CF remain
constant or the abscissas of points A, B, D
and E. The ordinates of tpoints C and F
remain stationary as assigned by the
geometry.
Newsletter EnginSoft Year 9 n°4 -
Table 2 - Table of results for optimal pressure and optimal noise reduction
based on DOE
21
Table 3 - MDO results based on the NSGA-II analysis
The range of variations of the free parametersis as follows:
• dx_CF varies from -5 mm to +25 mm in steps of 10 mm (5 mm, +5 mm, +15 mm, +25 mm)
• dy_AB ranges from -10 mm to +20 mm in steps of 10 mm
(-10 mm, 0 mm, +10 mm, +20 mm)
• dy_DE ranges from -10 mm to +20 mm in steps of 10 mm
(-10 mm, 0 mm, +10 mm, +20 mm)
The challenge of the optimization has been a multidisciplinary and multi-objective problem: the disciplines
involved have been fluid dynamics and acoustics, the
objectives were minimizing the pressure drop (p_in - p_out)
and minimizing the level of noise emitted from outlets and
walls.
Fig. 18 - Parallel Coordinates Chart optimization
Fig. 18 - Acoustic analysis for the outlet
Fig. 17 - Parallel Coordinates Diagram for the restriction of the domain
space of pressure loss and noise
Results
A 4 level full factorial DOE has been carried out on the 3
variables, which means that 64 configurations have been
tested (43 = 64 experiments). Following are the results which
represent a significant improvement to the previously
adopted design. The minimum pressure drop (corresponding
to the configuration process number 9) and the minimum
sound level (corresponding to the configuration process
number 59) are shown in Table 2.
From the table, it becomes clear that the two objectives
cannot be achieved simultaneously, as the minimum pressure
drop is far from the minimum level of noise produced by the
walls (Table 2). Therefore, the analysis moved on to a
Multidisciplinary Design Optimization MDO.
Outlet MDO
To refine the research of the investigation it has been decided
to filter the results by imposing the limits of acceptance for
the pressure drop in relation to the level of noise emitted
from the walls. The filtering action narrowed the range of
variations. This effect is shown in the filters operating
diagrams in Figure 17, where the parallel coordinates were
Fig. 19 - Outlet CFD analysis for pressure drop
reduced to a range of 3 to 28 dB noise levels and a maximum
pressure drop of 4 Pa.
As before, the three parameters that vary have been dx_CF,
and dy_AB dy_DE, while the other 3 parameters, dx_AB, and
dx_DE dy_CF, remain constant, or the abscissas of points A,
B, D and E.
• dx_CF ranges from +12.5 mm to +25.0 mm in steps of 2.5
mm
• dy_AB varies from -2.5 mm to +12.5 mm in steps of 2.5 mm
• dy_DE varies from -2.5 mm to +12.5 mm in steps of 2.5 mm
The optimization has been performed by implementing the
Non-dominated Sorting Genetic Algorithm II (NSGA-II) with
Case Histories
22 - Newsletter EnginSoft Year 9 n°4
treatment) of roughly 2 million cells has
been constructed.
•
Boundary condition definition: all
operating conditions. In this paper, we
show the results of the boundary
conditions, they are reported in Figure 20.
Furthermore, an internal macro has been
developed and embedded into StarCCM+ in
order to simulate the physiology of the
passenger in terms of heat load and % of
humidity released.
•
Physics model: steady state, KEpsilon with two layers, all Y+ wall
treatment, multi-phase model (air/water),
segregated flow with radiation model.
Fig. 20 - Simplified CAD model and Boundary condition
10 generations in a population of 8 configurations chosen
from the best, previously tested in the DOE analysis.
Results
The results of the best iteration in minimum pressure drop
(corresponding to the configuration process number 130) and
in minimum sound level (corresponding to the configuration
process number 82) are presented in Table 3.
The aim of the analysis has been the study of the A/C cabin,
we have analyzed and verifyied the following parameters:
• Velocity field (see Figure 21)
• Relative humidity pattern (see Figure 22)
• Temperature pattern in cabin zones (see Figure 23).
• Cabin average temperature
The Parallel Coordinates in the diagram of Figure
18 illustrate the results for the r80 run
configurations generated for the optimization.
Figure 18 shows the acoustic FEA analysis, and
Figure 19 shows the CFD pressure losses
analysis.
Evaluation of the A/C cabin thermal
environment and the occupants’ thermal
comfort
Once the design of the air distribution system
and of the air conditioning pack were
completed, the final steps have been the
evaluation of the cabin thermal environment
and the passengers’ comfort assessment.
This activity has been developed through the
following steps:
• Tri-dimensional cabin thermal model
development.
• Assemby of a complete mono-dimensional
model.
• Comparison between the two approaches.
Tri-dimensional CFD cabin thermal model
The tri-dimensional cabin thermal model has
been developed in the StarCCM+ environment,
through the following steps:
• Domain definition: due to its symmetry, a 2
meter long section of the cabin has been
analyzed.
• Mesh construction: in order to study, in
adequate detail, the distribution of velocity,
temperature and humidity, a polyhedral
mesh (with a prism layer for turbulence
Case Histories
Fig. 21 - Velocity field
Fig. 22 - Relative humidity pattern
Newsletter EnginSoft Year 9 n°4 -
23
temperature calculated with the CFD analysis is
comparable with the average temperature
calculated with the mono-dimensional model,
assuming the same input conditions.
The CFD model allowed to obtain a detailed
evaluation of the cabin thermal environment,
the temperature stratification, the stagnation
zones, and the thermal environment near the
passengers for evaluating the status of the
passenger comfort.
The mono-dimensional thermal model allowed,
in a sufficiently accurate way, to obtain a fast
evaluation of the cabin thermal environment in
terms of average temperature and % of
humidity.
Fig. 23 - Temperature pattern
Passenger comfort requirements imposed by the aeronautical
rules are:
• Differential temperature between aft and forward side are
not to exceed 2°C
• Differential temperature between head and feet are not to
exceed 3°C.
• Differential temperature between left and right side are
not to exceed 2°C.
Considering as boundary conditions the data reported in
Figure 20, our CFD model provides the following results:
• Average relative humidity: 36.37%
• Cabin average temperature: 23.8°C
• As shown in Figure 23, the compliance with comfort
requirements described above could be guaranteed.
Complete ECS system mono-dimensional model.
The complete mono-dimensional model has been obtained by
linking the air conditioning pack model (see Figure 4) with
the air distribution system model (see Figure 10), and with
the A/C thermal model shown in Figure 6.
The aim of the analysis was to study the A/C cabin thermal
environment, analyzing and verifying the following
parameters:
• Average relative humidity
• Cabin average temperature
The analyses have been performed at different A/C and flight
conditions.
Considering as boundary conditions the data reported in
Figure 20, our mono-dimensional model delivered the
following results:
• Average relative humidity: 40%
• Cabin average temperature: 24.1°C.
Results
In order to evaluate the mono-dimensional model results (low
fidelity model), its results have been compared with the CFD
tri-dimensional model results (high fidelity model). The
performed analysis has highlighted that the average
Conclusions
Various new frontiers are currently emerging in the aerospace
industry. They require new initiatives and approaches for the
role of engineering design and analysis, mainly due to the
profound knowledge of the importance of cross-firms and
cross-disciplines collaboration in large scale engineering
design processes, such as aircraft design. This kind of
collaboration and interaction is now more possible than ever
before due to the current state of digitization of engineering
design data, an IT infrastructure that enables a universal
communication of data, the current engineering platforms
which support collaboration, and the increasing
computational power, which allows us to integrate
multidiscipline, multi-physics and engineering data in one
shared environment. This state-of-art design environment is
leading to a new opportunity, and to a challenge. As the
present study shows, process integration between different
design disciplines is an essential factor for automating design
processes.
The design process presented in this paper is actually used in
the Environmental Control System department of Alenia
Aermacchi, where fluid dynamic problems are approached
with innovative tools and innovative methodologies that
allow to define the architecture and to optimize the
performance from the early stages of the system design.
The described approach allowed to achieve the following
reported goals:
• Reduction/elimination of physical tests and related costs
during the development phase.
• Minimization of certification tests.
• Minimization of risks and costs linked to the re-design of
parts in the manufacturing phase.
Alenia Aermacchi S.p.A. – G. Mirra, P. Borrelli, A. Romano
Politecnico di Torino – M. Tosetti, L. Pace
Università del Salento – B. Palamà, A. Camillò
For more information:
Francesco Franchini, EnginSoft
[email protected]
Case Histories
24 - Newsletter EnginSoft Year 9 n°4
How Geometrical Dimensioning &
Tolerancing influence the
performances of an
electromechanical contactor
return stable coupling of fixed parts, adequate freedom of
moving parts and appropriate room to house electrical parts. For
simplicity, we will call “functioning measurements” all those the
contactor dimensions from which its reliable operation depends.
In other words, if one or more functioning measurements is not
comprised between assigned limits, the contactor assembly does
not work properly and has to be rejected.
Lovato Electric has been a prestigious Italian company operating
Generally speaking, overall dimensions (including the
in the electromechanical and electronic components market for
functioning measurements) of a multi-part assembly depend on
more than 90 years. Its wide catalog includes magneto-electric
how both surfaces and edges of adjacent parts touch
switches, contactors, sensors, digital multi-meters, soft-starters,
themselves. From this point of view, the study of the assembly
relays, automatic power factor correctors and other devices. Top
geometrical properties becomes a tridimensional problem, whose
quality, reliability and product variety make Lovato Electric a
complexity grows with the number of contacts and shape of the
star player in the world market. Company success is gained
involved features. If parts had nominal shape, then the
through constant valorization of internal competences and
assembly would be univocally determined and solved by using
parallel effective collaboration with customers and suppliers.
any CAD tool. Real assembly conditions are far from the ideal
In a past engineering service, EnginSoft was requested by
ones, because real geometries exhibit a certain dispersion due
Lovato Electric to investigate how the operation of an
to the manufacturing processes. As a consequence, the assembly
electromechanical contactor is influenced by dimensional and
output is no longer univocally determinable and functioning
geometrical tolerances of its components (GD&T analysis).
measurements become dispersed as well. The contactor designer
Electromechanical contactors constitute a relevant fraction of
controls and limits the variability of the functional
Lovato Electric production, so that the topic was perceived as of
measurements (trying to keep them between the acceptance
primary importance.
limits)
by
assigning
proper
An electromechanical contactor is a
dimensional
and
geometrical
compact device including an
tolerances to the components. The
electromagnetic
actuator
investigation of how tolerances affect
mechanically connected to a set of
the dispersion of the functioning
contacts. When the command signal
measurements is carried out through a
(a low power current) activates the
statistical approach.
internal inductor, a piston moves and
change the connected contact status.
The contactor that has been analyzed
in the consulting service is composed
Typically, this device is used to break
a power circuit from changes
by existing parts (i.e. taken from other
production lines) and specifically
location, without manually accessing
designed new parts. EnginSoft
the switch. The contactor is
contribution has made possible to
composed by both plastic and
predict both mean values and
metallic components held together by
dispersions of the 5 functioning
snapfeatures and screws. Plastic parts
are manufactured by injection
dimensions selected by the customer
and shown in Figure 1. At the same
molding process, while metallic parts
time, an extensive sensitivity analysis
are manufactured by cold forming of
has made possible to identify the
sheets. The contactor works reliably if
factors influencing these dimensions,
the assembly process creates both
which are the key information to
precise clearances and precise
assess corrective strategies in case of
interferences between parts, where
unsatisfying distribution of the
they are necessary.
Fig. 1 - Contactor section highlighting the 5
outputs.
Indeed, these geometrical conditions functioning measurements
Case Histories
Newsletter EnginSoft Year 9 n°4 -
The service was completed through different tasks. First, the 3D
CAD model was analyzed in detail to understand how the
components interact and to select the surfaces involved in the
contacts. Then, the dimensional chains were written
accordingly. Each dimensional chain provides a vectorial
representation of the geometrical relationships between
component dimensions and functional measurements. For the
analyzed device, it was found that 35 dimensions (among
hundreds available) were affecting the functional
measurements. As expected, the 5 dimensional chains resulted
to be interdependent, since some dimensions were
simultaneously included in more than one relationship. At the
end of the problem definition, a virtual model of the contactor
was developed, and the values of the 5 functioning
measurements were calculated.
A model used to investigate GD&T problems needs to faithfully
reproduce geometrical interactions between parts. In order to
meet such requirement, the virtual assembly is performed by
putting into contact both surfaces and edges, instead of
aligning planes and axes as we normally do in a CAD
environment. The hardest phase of such work, which is also the
deeper added value of this service, is really the mathematical
description of the tridimensional interactions between
component features.
The model is finally parameterized, so that it includes the
variability (in terms of position and size) of all geometrical
details involved in the contact definition. Virtual measurements
can be taken easily, in accordance to the model purposes. It is
not difficult to see that a model with the mentioned
characteristics, virtually reproduces any possible configuration
of the multi-part assembly. From a different perspective, we
could look at the model as to a numerical representation of the
dimensional chains previously identified: it correlates the
outputs (i.e. the functioning measurements), to the inputs (i.e.
the component dimensions).
The statistical investigation of the GD&T problem was carried
out by assigning a normal distribution to each dimension of the
components. This was an arbitrary choice, since we did not have
information about. Obviously, we could have assigned any kind
of distribution to each dimension. Mean values were picked in
the middle of the corresponding tolerance ranges, while
standard deviations were assumed as equal to 1/6 of the widths.
These assumptions relate to the quality of the manufacturing
processes we consider. By filling the tolerance range with 6
standard deviations, we implicitly assume that just 1 component
out of every 370 has the considered dimension out of its
tolerance. We investigated how tolerance effects propagate to
the functioning dimensions, by generating a huge number of
device configurations in a limited time. Distributions of the 5
outputs were then compared with the given acceptance limits,
in order to identify the percentages of devices fulfilling the
requirements.
Main results are collected in Figure 2, the distributions of the 5
functioning measurements are compared to the corresponding
requirements. All distributions are still of normal type, with
symmetric shape. Plots highlight that significant fractions of the
entire production are not meeting the operational requirements.
25
Fig. 2 - Distributions of functioning measurements in the virtual production
The probability for a contactor to not be accepted after
assembly is about 37%, mainly because the measurement n. 4
goes out of its acceptance limits. Plots of Figure 2 shows that
non conformities can be caused by both an excessive width of
the distribution (FUNC.MEAS.3) or a misalignement of the mean
value with the acceptance range (FUNC.MEAS.2 and
FUNC.MEAS.4).
The statistical sensitivity analysis carried out on the population
has made possible to select the dimensions (among the 35
involved) with the highest influence on the 5 outputs. Thus,
appropriate adjustments were assessed to reduce the risk of
non-conformity. In particular, the mean value of FUNC.MEAS.4
was moved to right (almost making null the area lying out of the
acceptance bounds) by adjusting the nominal value of 2
component dimensions. This result really highlights the power of
the GD&T analysis: an assembly issue is fixed with no need to
narrow tolerance ranges. In other words, the reduction of
rejected devices is obtained without increasing manufacturing
costs. In this example, the collaboration between Lovato
Electric and EnginSoft has returned valuable benefits. EnginSoft
has simulated the assembly process through advanced numerical
tools, providing crucial information about the relationships
between component dimensions and final contactor
performances. As issues were identified, proper corrections were
planned and verified immediately. This has allowed Lovato
Electric to shorten the physical prototyping phase, which turned
into an effective reduction of overall production costs.
For more information:
Fabiano Maggio - EnginSoft
[email protected]
Case Histories
26 - Newsletter EnginSoft Year 9 n°4
Research Activities on Slot-Coupled
Patch Antenna Excited by a Square Ring Slot
A novel slot-coupling feeding technique for wideband dualpolarized patch antennas is presented. A square patch is fed
through a square ring slot excited by two non-overlapping
feeding lines printed on the same side of a single-layer
substrate. Reflection coefficient, port isolation and radiation
patterns are evaluated by numerical simulations with ANSYS
Designer and compared with measurements on an antenna
prototype operating at the WiMAXTM 3.3-3.8 GHz frequency band
(14% impedance bandwidth). Based on the slot coupled feeding
technique, the following antennas have been designed and
prototyped: a 2x2 array of dual-feed circularly-polarized square
patches, a single-feed circularly-polarized square patch, also in
a stacked version, a 2x2 array of dual-polarized circular patches
fed through a circular slot, a 2x1 array of stacked square
patches fed through square slots.
1. INTRODUCTION
The last years have seen a significant exploitation of printed
antenna technology in mass production of planar arrays for base
stations and subscriber units of cellular communication
systems. Indeed, microstrip antennas are characterized by low
profile, light weight, easy construction, and high flexibility in
designing shaped-beam and multiband antennas. Although
there are some considerable concerns regarding the microstrip
antenna inherently resonant feature, a number of efficient
techniques have been proposed to meet the large impedance
bandwidth requirement of modern broadband communication
systems. Furthermore, several dual-polarized patch
Fig. 1 - Some configurations of dual-polarized slot-coupled patch antennas,
with different positions of the two coupling slots with respect to the patch
center. Feeding lines with the same color are printed on the same side of
the dielectric slab; in X1 an air bridge is needed to avoid line overlapping.
Case Histories
configurations have been designed to be used as radiators in
arrays for polarization-diversity based radio links. A common
feeding technique for wideband antennas is based on slotcoupling, where a microstrip line is coupled to the radiating
patch through a slot in a metallic ground plane, as first
proposed by D.M. Pozar. Slot-coupled patches can exhibit a
quite large impedance bandwidth at the cost of an affordable
construction complexity, and allow for more space for the feed
network with respect to microstrip fed arrays (the latter being
an important need especially for dual-polarized dense phased
arrays). Moreover, the metallic slot plane prevents the spurious
radiation from the feed network and then reduces the amplitude
of the cross-polar components. Finally, the two-layer structure
allows for using a thick low-permittivity substrate for the patch
(which guarantees a larger impedance bandwidth and a higher
efficiency) and a thin high-permittivity substrate for the feed
circuitry (as required to suppress radiation from the feed line
and to save space for the feed circuitry). To extend the singlefeed, single-polarization design to the dual-polarization
antenna design, a large number of aperture-coupled patch
antennas have been presented in the open literature (most of
them are shown in Figure 1).
Dual-polarized microstrip antennas require the excitation of the
two orthogonal fundamental modes of a microstrip patch. Dualmode excitation can be obtained by coupling the radiating
patch to the feeding network through two orthogonal slots in a
metallic ground plane: either a cross-shaped slot or separated
orthogonal slots have been used. Besides gain and radiation
pattern values, design concerns are also about the port
isolation and the cross-polarization level, since they impact on
the communication system performance. Both above properties
are markedly related to the electrical and the geometrical
symmetry properties of the antenna layout with respect to the
principal radiation planes. Moreover, a symmetry property of the
antenna with respect to the two input ports is also a valuable
feature, as in this case the two polarization ports exhibit
identical impedance and radiation characteristics. In this paper
a novel dual-polarized slot-coupled feeding technique is
presented. With respect to other slot-coupling feeding
techniques for dual-polarized patch antennas, the proposed
configuration exhibits a simple structure and a valuable
Newsletter EnginSoft Year 9 n°4 -
symmetry property with respect to the two feeding ports, while
preserving a satisfying isolation between them (greater than 20
dB). A square patch is coupled to a pair of microstrip feeding
lines by a square ring slot realized in a metallic ground plane,
and both feeding lines are printed on the same side of a singlelayer substrate. Antenna layout performance is shown for a
design relevant to a patch operating in the 3.3-3.8 GHz
WiMAXTM frequency band. Simulation data agree with
measurements on an antenna prototype. The proposed coupling
technique is suitable for the design of large planar arrays with
dual linear polarizations (vertical/horizontal polarizations or
45° slanted polarizations). Dual circular polarization can also
be implemented by adding a 90° hybrid coupler.
ANSYS Designer is the electromagnetic simulator code used for
all patch antennas design. The physical quantities taken into
account in all projects are the reflection coefficient, the
isolation between the two channels in the dual polarization
configurations, the axial ratio for circular polarized antennas,
the gain and directivity, the 3D radiation patterns and the Eθ
and Eφ components in the two principal antenna planes, the
back radiation, the side lobes level. Each antenna element is
parameterized in order to analyze each parameter effect on the
antenna performance and in order to simplify the optimization
process. For example, thanks to the parameterization,
modifying the distance between two array elements elements is
not necessary to re-design the feeding network. The simulated
results are very close to the prototype measurements, also
avoiding systematic errors that are committed in the
measurement process, as implementation prototype errors,
welds discontinuities, etc.
The article is organized as follows. The novel slot-coupling
feeding technique and its working principle are illustrated in
Section 2 together with simulated results obtained with a fullwave commercial tool and with measurements on an antenna
prototype. Section 3 describes the new feeding technique
applications to some circular polarized arrays and stacked
antenna. Finally, concluding remarks are drawn in Section 4.
2. A Square Ring Slot Feeding Technique
The novel dual-polarized slot-coupled patch antenna fed
through a square ring slot is shown in Figure 2. Both feeding
lines are printed on the same side of a single layer substrate
and a metallic reflector is added to limit the back radiation. It
is apparent that the layout is symmetric with respect to the two
input ports, which means that identical radiation and input
impedance properties are expected. The latter represents a
useful feature when designing a circular polarized patch
(requiring an additional feeding circuit to generate two signals
with the same amplitude and a 90° phase shift), or when
designing the feeding network of a dual-polarized array.
Moreover, since the slot and patch phase centers overlap, the
radiation pattern main direction is not depointing at any
frequency.
The radiating elements are fed in ANSYS Designer through an
edge port inserted between the microstrip line (printed on the
dielectric substrate upper surface) and the antenna ground
plane (on the other side of the same substrate). The proposed
27
Fig. 2 - The square patch fed through a square ring slot: (a) stackup and
(b) layout. Dimension of the geometrical parameters for a 3.5 GHz WiMAXTM
antenna: P=22 mm, L=17 mm, K=0.5 mm, W1=2.5 mm, W2=3.7 mm, S1=2
mm, S2=6 mm, H1=22 mm, H2=11 mm.
feeding technique allows to simultaneously feed the patch by
using two orthogonal microstrip lines, furthermore the above
lines can be properly connected to get circular polarization. To
evaluate the isolation between these two channels and to
analyze separately the Eθ and Eφ components contribution
generated by the two microstrip lines, it was necessary to insert
two edge ports. To show the working principle and the radiation
properties of the proposed slot-coupled patch, a sample
antenna operating at the 3.3-3.8 GHz WiMAXTM frequency band
has been designed, fabricated and characterized. It is worth
noting that the proposed geometry can be used for any
application requiring a planar dual-polarized antenna with a
10-15% fractional bandwidth (larger impedance bandwidth can
be also obtained by adding a square stacked patch) and a 20 dB
port isolation.
In the sample antenna, both microstrip lines are printed on the
same 90x90 mm2 Rogers RO4003 laminate (εr=3.55,
tanδ=0.0027, thickness=1.524 mm), available in the ANSYS
Designer material library. The low loss Roger RO4003 used for
the antenna active part, although more expensive, allows to
obtain higher antenna gain thanks to lower feeding line losses.
Instead, the low cost FR4 was used to print the patches,
electromagnetically coupled to the microstrip line. The stackup
is shown in Figure 2a. The square ring slot has a perimeter of
68 mm (Figure 2b) and it is etched on the other side of the
above substrate, namely on the metallic ground plane
separating the feed lines from the square patch. As in other
slot-coupled patch configurations, the ground plane prevents
spurious radiation from the feed network and the length of the
open-circuited stub behind the slot is optimized for input
impedance tuning. A 160x160 mm2 square aluminum reflector
is placed at a distance of 22 mm from the feed lines to reduce
back radiation and increase the antenna gain. The 22x22 mm2
copper patch is printed on the bottom layer of a 90x90 mm2
FR4 laminate, which is 1.6 mm thick (it also acts as a cover for
the antenna). The air gap between the patch and the slot plane
is 11 mm thick. Figure 3 illustrates the electric field
distribution inside the square ring slot when Port1 of the patch
in Figure 2 is fed. It is apparent that the field distribution
resembles that of the fundamental resonating mode of a ring
slot. This is in agreement with the slot perimeter length that is
close to the guided wavelength λg of a slotted line with the
Case Histories
28 - Newsletter EnginSoft Year 9 n°4
same geometrical and electrical parameters as those of the slot:
Oviedo. The frequency set for the mesh was thus chosen as 5
λg=66 mm at 3.5 GHz. The electric field distribution shown in
GHz, which was a good compromise between mesh accuracy and
Figure 3 reveals a number of interesting features. The side of
simulation times (Figure 5). The sweep analysis was varied from
the ring slot that is directly fed and that one parallel to it (i.e.
3000 to 4000 MHz.
the vertical sides of the ring slot shown in Figure 2b) are both
excited, and the electric field induced into the two slot sides
Both measured and Designer simulated results for the reflection
are in phase and with a similar amplitude; as a consequence,
coefficient and port isolation are shown in Figure 6, and they
due to above phase relationship and the symmetric position of
exhibit a reasonable agreement. For both polarizations, the
the vertical sides with respect to the
reflection coefficient is less than -10 dB,
patch center, the resonant mode of the
from 3.3 GHz to 3.8 GHz (percentage
patch (that one associated to Port1) is
impedance bandwidth is 14%). The port
properly excited and low crossisolation is greater than 20 dB in the whole
polarization is expected. Moreover, the
3.5 GHz WiMAXTM frequency band.
electric field distribution induced into the
In Figure 7, the co-polar and cross-polar
two sides of the slot orthogonal to the
components of the radiation patterns, in the
previous ones (i.e. the horizontal sides of
θ=45° and θ=-45° radiation planes, are
the ring slot shown in Figure 2b) are out
shown, when Port2 is fed (indeed, dual-linear
of phase and do not excite the orthogonal
polarized antennas are usually used to
resonant mode of the patch (that one Fig. 3 - Direction and amplitude of the electric
implement base station antennas with ±45°
associated to Port2). Finally, the induced field inside the square ring slot, when Port1 of
slanted polarizations). Measured half power
electric field does vanish close to the the antenna in Figure 2 is fed (ANSYS Designer
beamwidth at 3.55 GHz is around 56° in both
data).
center of the horizontal sides of the slots;
planes and cross-polar components are below
Fig. 4 - A square ring slot antenna prototype for
3.5 GHz WiMAXTM applications.
Fig. 5 - Antenna mesh at 5 GHz.
it means that a relatively high port isolation is expected when
that point is used to couple the slot ring to the orthogonal feed
line corresponding to Port2. It is worth noting that since the
slot perimeter is less than the free-space wavelength (actually
it is around a slot-line guided wavelength) and the patch
perimeter is almost double the free-space wavelength, the
whole square ring slot does always remain under the patch, for
any design frequency. Finally, due to the perfect symmetry
between the two ports, the same radiation patterns (in both E
and H planes) and the same gain for the two ports are expected
in the whole antenna frequency bandwidth.
The presented novel layout can be seen as an advancement of
“O” configuration in Figure 1. Indeed, it is apparent that the
four-slot arrangement, symmetric with respect to the patch
center, resembles the ring slot geometry. The significant
difference is that in the novel configuration all four sides of the
ring slot contribute effectively and correctly to the excitation
of the two orthogonal fundamental patch resonant modes, while
in the “O” configuration two of the four slots are parasitic
elements. A 3.5 GHz WiMAXTM prototype (Figure 4) has been
realized and measured in the anechoic chamber at the
Department of Electrical Engineering of the University of
Case Histories
Fig. 6 - Measured and simulated S-parameters of the
square ring slot patch.
-18 dB in the broadside direction. Measured gain is between 8
dB and 8.7 dB in the band of interest (Figure 8). Similar results
are obtained when Port1 is fed.
3. Square Ring Slot Technique Applications
Basing on the ring-slot coupled feeding technique, the
following antennas have been designed and prototyped: a 2x2
array of dual-feed circularly polarized square patches (Figure 9),
a single-feed circularly polarized square patch, also in a stacked
Fig. 7 - Measured and simulated co-polar and cross-polar components for the
square slot patch in Figure 2, at f=3.55 GHz when Port2 is fed: (a) θ=45°
plane and (b)θ=-45° plane.
Newsletter EnginSoft Year 9 n°4 -
29
version (Figure 10), a 2x2 array of dualdesigned to increase the percentage
polarized circular patches fed through a
bandwidth up to 44.5% in order to be
circular slot (Figure 11), a 2x1 array of
used at base stations where wideband
stacked square patches fed through square
antennas are needed (e.g. base stations
slots (Figure 12). In Figure 9, the sequentially
for GSM, PCS, UMTS, WLAN applications).
rotated 2x2 array prototype with a complete
The simulation times, for all the
microstrip feeding network is shown. Each
antennas designed and presented in this
dual-linear polarized patch has been fed
paper, vary between 15 and 60 minutes,
through a reactive 3 dB power divider in order
depending on the antenna operating
to have a single feeding line. The feeding
band and the radiating elements number
network consists of microstrip lines whose Fig. 8 - Measured and simulated gain of the
in the configuration. The ANSYS Designer
square ring slot patch in Figure 2, when Port2
lengths have been adjusted to achieve the is fed.
simulation process has saved a lot of
required 90° current phase difference
time: the prototype procedure (up to
between adjacent elements. To get a wide impedance and wide
connectorization process) and measured process is very
axial ratio bandwidth, a sequential rotation feeding technique
onerous: the prototype process was about 60 minutes, the
has been adopted. A single feed slot-coupling solution has
radiation patterns measurements component for a single plane
been applied to gain circular polarization. A meandered slot is
at a single frequency was about 2 minutes). Then this procedure
designed to excite two orthogonal modes and the same kind of
was repeated for each plane, both the components and the
perturbation is applied to the patch. To preserve the antenna
entire band of interest. Moreover, it is necessary to take
symmetry, two identical meanders have been added on two
account of the entire prototyping and measurement cost (the
opposite sides of the square ring. Both width and length of the
materials cost, the instrumentation, the available facilities). It
above slots have been optimized. To improve axial ratio
was therefore fundamental to get to the measurement stage
performance, a stacked solution has been proposed (Figure 10)
with reliable projects, obtained with ANSYS Designer.
to get a 12% 3 dB axial ratio bandwidth.
Basing on Figure 9, the configuration shown in Figure 11 is
4. CONCLUSIONS
designed with both circular slot and patch. The performances of
A novel wideband slot-coupled patch fed through a square ring
the two configurations are shown and compared for two
slot has been presented and design criteria have been
fabricated prototypes. Antennas shown in Figure 9 and Figure
discussed. Owing to its simple structure, the patch described
11 have been designed to operate in the WiMAXTM frequency
here can be used as the radiating element of medium and large
band around 3.5 GHz. The configuration shown in Figure 12 is
planar arrays with dual linear polarizations (vertical/horizontal
a 2x1 array of square stacked patches. This antenna has been
polarizations or ±45° slanted polarizations). Antenna
performance in terms of port isolation and cross-polar
component level has been shown through the design,
fabrication and characterization of a patch operating at the
3.3-3.8 GHz WiMAXTM frequency band. A 20 dB port isolation
has been obtained, in a 500 MHz frequency band (14%
fractional bandwidth), with cross-polar level less than -18 dB at
the broadside direction. We have also experienced that the final
design of the proposed solution is a result of a trade-off
between frequency bandwidth enlargement and isolation
improvement. Impedance bandwidth enlargement can be
Fig. 10 - Single-feed circularly polarized achieved by adding either stacked patches or other parasitic
Fig. 9 - 2x2 array of dual-feed
stacked square patch for 3.5 GHz
circularly polarized square patches
elements close to the main radiating patch, while preserving
WiMAXTM applications.
for 3.5 GHz WiMAXTM applications.
the original symmetry properties. Finally, due to the symmetry
of the antenna layout with respect to the two
feed ports, good axial ratio performance can be
obtained when it is used to radiate a circularly
polarized field.
R. Caso, A. Buffi, P. Nepa - Department of
Information Engineering, University of Pisa
A. Serra - EnginSoft
Fig. 11 - 2x2 array of dual-polarized
circular patches fed through a
circular slot for 3.5 GHz WiMAXTM
applications.
Fig. 12 - 2x1 array of stacked square patches fed
through square slots for GSM, PCS, UMTS, WLAN
applications.
For more information:
Andrea Serra, EnginSoft
[email protected]
Case Histories
30 - Newsletter EnginSoft Year 9 n°4
Grapheur for Material Selection
In this article the criteria of mechanical behavior of the
MCDM for Material selection
woven textile composites during the draping and the further
When multiple criteria from different disciplines are to be
involved simulations and analysis are included in the process
satisfied in a material selection problem, often complexities
of the optimal design and decision making. For this
purpose, the advanced software architecture of
Grapheur for interactive optimization and MCDM is
utilized. In this software the identified challenges
of utilizing MCDM are improved via connecting the
data mining/visualization and optimization
through the user interaction. For the optimal Fig. 1 - Simulation of the draping process
design of composites, with the aid of advancement
of interdisciplinary and data analysis tools, a series
of criteria including mechanical, electrical,
chemical, cost, life cycle assessment and
environmental aspects aspects can now be
simultaneously considered. As one of the most
efficient approaches, the MCDM applications can
provide the ability to formulate and systematically Fig. 2 - A combination of four different simulation criteria including the compression, bend,
compare different alternatives against the large stretch, and shear form the draping a) Mechanical modeling of the bending; the behavior of
sets of design criteria. However, the mechanical textile under its weight is simulated by manipulating the related geometrical model within
behavior of woven textiles during the draping the CAGD package. b) Geometrical model
increase due to criteria conflicts. Many applications and
process has not yet been fully integrated into the optimal
algorithms of MCDM have been previously presented to deal
design approaches of the MCDM algorithms.
with decision conflicts often seen among design criteria in
material selection. However, many of the identified
Introduction
In the integrated engineering design process and optimal
drawbacks and challenges are associated with the
applicability.
design, the material selection for the composite can
determine the durability, cost, and manufacturability of final
products. The process of material selection begins with
Draping
indentifying multiple criteria properties of mechanical,
The manufacturing of woven reinforced composites requires a
electrical, chemical, thermal, environmental and life cycle
forming stage so-called draping, in which the preforms take
costs of candidate materials. However, the mechanical
the required shapes. The main deformation mechanisms
behavior of woven textiles during the draping process has
during forming of woven reinforced composites are
not yet been fully integrated into the optimal design
compression, bend, stretch, and shear which cause changes
approaches of the MCDM algorithms.
in orientation of the fibers. Since fiber reorientation
Case Histories
Newsletter EnginSoft Year 9 n°4 -
31
Fig. 3 - Geometrical modeling of double dome utilizing the Khabazi [11] algorithm.
influences the overall performance, it would be an important
factor that should be taken into account along with the other
criteria.
Mechanical modeling and simulation of the draping
The mechanical models of drape involve much higher
computational cost when compared to the kinematic models;
yet, they offer the benefit of representing the non-linear
material behavior. Moreover the mechanical simulation, as
the most promising technique, gives a real-life prediction of
the fiber reorientation.
Geometrical modeling and simulation of the woven textiles
Moreover, of all the approaches for the geometrical modeling
of woven textiles presented so far, the Spline-based methods
are the most effective technique. In fact, the Spline-based
geometrical representation of a real-life model of any type of
flat-shaped woven textile, is realized by implementing the
related computer-aided geometrical design (CAGD) code.
However, the mathematical representation of a woven
multiple-dome shape, in the practical scale, may not be
computationally valid.
In order to handle the computational complexity of
geometrical modeling the multiple-dome woven shapes,
utilizing the NURBS-based CAGD packages are essential.
Khabazi introduced a generative algorithm for creating these
complex geometries. His improved algorithm is capable of
producing the whole mechanism of deformation with
combining all details of compressed, bended stretched and
sheared properties. It is assumed that if the mechanical
behavior of a particular woven fabric of a particular type and
material is identified then the final geometrical model of the
draping could be very accurately approximated. In this
technique the defined mechanical mechanisms of a particular
material, in this case glass fiber, is translated into a
geometrical logic form integrated with the NURBS-based
CAGD package through a process called scripting.
Integration the MCDM-assisted material selection
with draping simulation
In order to select the best material of a woven textile, the
draping simulation needs to be carried out for a number of
draping degrees. The results of all the draping simulations of
different drape angles are gathered as a data-set for
consideration, in addition to already existing data-sets from
the earlier study case, including the latter criteria i.e.
mechanical, electrical, chemical, cost, life cycle assessment
and environmental.
Visualization; an effective approach to MCDM and
material selection
Visualization is an effective approach in the operations
research and mathematical programming applications to
explore optimal solutions, and to summarize the results into
an insight, instead of numbers. Fortunately, during the past
few years, huge developments in combinatorial optimization,
machine learning, intelligent optimization, and reactive
search optimization (RSO) have taken place, which have
moved advanced visualization methods forward.
Previous work in the area of visualization for MCDM allowed
the user to better formulate the multiple objective functions
for large optimization runs. Alternatively, in our research
utilizing RSO, which advocates the learning of optimization,
the algorithm selection, adaptation and integration are done
in an automated way and the user is kept in the loop for
subsequent refinements. Here, one of the crucial issues in
MCDM is to critically analyze a mass of tentative solutions
Fig. 4 - Mechanical modeling of draping process for a number of draping degrees
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32 - Newsletter EnginSoft Year 9 n°4
design, modeling, and decision-making. The
software has implemented a powerful
interface between a generic optimization
algorithm and decision maker. While
optimization systems produce different
solutions, the decision maker is pursuing
conflicting goals and tradeoff policies
represented on the multi-dimensional
graphs.
Conclusions
The utilization of a software architecture
for MCDM, including the mechanical modeling of the draping,
with a particular emphasis on supporting flexible
visualization has been discussed.
The applicability of the software can be easily customized for
different problems and usage contexts. The preliminary tests
of the software environment, in the context of designing a
multiple dome shape, have shown the effectiveness of the
approach in rapidly reaching a design that meets the
expectations of the decision maker.
Fig. 5 - a) Parallel chart considering five optimization objectives b) The 7D visualization graph
which are visually mined to extract useful information.
Concerning the solving of the MCDM problems, the final user
is not distracted by technical details, but instead
concentrates on using his expertise and informed choice for
the large number of possibilities.
Software architecture of the proposed reactive
and interactive MCDM
The proposed software is based on a three-tier model,
independent from the optimization package, called Grapheur
which is an effective and flexible software architecture for
integrating problem-solving and optimization schemes into
the integrated engineering design processes and optimal
Amir Mosavi, Miklos Hoffmann, Atieh Vaezipour
University of Debrecen, Hungary
LIONsolver by Reactive Search Srl: the "Big Data" challenge and opportunity
Nowadays, more and more enterprises can afford to enlarge
their data storage means at will. Information that a few years
ago would have been thrown away is now kept in the main
storage area, ready to be retrieved and analyzed.
Enterprises are now discovering that they lack the means to
draw insights from this large amount of data: while storage room builds up nicely, communications and processing power
needed to extract useful information from data is beyond their
reach. Such power is now made available thanks to parallel
processing platforms such as Apache Foundation’s Hadoop,
however their use remains a big challenge for most organizations.
The LION difference: machine learning and optimization
Consider a web server farm as used by many enterprises. Every
webpage accessed by a visitor results in the addition of a line of text to a log file recording the instant of of the request,
its source, and many other pieces of information (similar logs
are produced by activity in social networks like Twitter,
Facebook, etc). Server logs keep growing and, to avoid unusably large files, they are broken into smaller files and eventually moved to different disks.
When the LIONsolver machine learning and optimization platform is combined with a Hadoop implementation for web log
analysis, previously unknown patterns emerge that show the
behavior of customers in a website. For example, event data,
Case Histories
such as video views, email registrations, or literature downloads can be correlated to engagement (time on site), pages visited and interacted with (suggesting the efficacy of web design) and ultimately with purchase follow through. As shown
below, LIONsolver drives the flow of data and computation in
the Hadoop system, visualizes the results once they are made
available by the framework, develops models by "learning
from data" and suggests improving strategies. LIONsolver goes beyond simple visualizations to show correlations that impact business decisions to inform customer and content targeting, web design, business rules, and so on.
For more information, visit http://lionsolver.com/ or contact
us at [email protected].
Newsletter EnginSoft Year 9 n°4 -
33
Studio di fattibilità produttiva attraverso
simulazione numerica di processo di forgiatura
Nello studio di processo di produzione per deformazione a caldo
di una forcella in acciaio C25 è stato affrontato anche il problema della resistenza a frattura duttile degli stampi. Eseguendo una
preventiva analisi del processo di produzione di una Forcella, è
stato possibile valutare l’influenza dei diversi parametri dell’intero processo produttivo, successivamente sono state condotte analisi FEM delle diverse fasi di progetto per poter definire gli stati
tensionali e deformativi del materiale in deformazione e degli
stampi, mediante codice numerico. Si sono potute così valutare le
diverse cause del fenomeno di bassa durata produttiva degli stampi, calcolando i valori di intensificazione delle tensioni nei punti
in cui nella realtà si verifica l’innesco della cricca. E’ stata inoltre
studiata l’ottimizzazione dell’intero processo, per ottenere un prodotto integro da difetti, un miglioramento del comportamento a
fatica degli stampi ottenendo benefici produttivi sia economici
che energetici.
Introduzione
I processi di lavorazione per deformazione plastica sono un campo di estremo interesse per le moderne tecniche CAE vista la
complessità teorica dei singoli processi e l’influenza dei vari parametri. In particolare il processo di deformazione a caldo di acciaio in stampi chiusi è stato storicamente uno dei primi processi investigati attraverso le tecniche di simulazione numerica. Ciò
soprattutto per l’elevato grado di ripetibilità della “massiva”
produzione di dato processo e dei numerosi parametri in gioco.
Un approccio di tipo FEM (Finite Element Method) è il più adatto allo studio del processo nel suo dettaglio, con la possibilità
di previsione delle tensioni e delle deformazioni indotte dalla lavorazione per deformazione plastica a caldo. L’applicazione di
tale metodologia è assai complessa, vista la non linearità di
comportamento del materiale che viene schematizzato con un
modello elasto-visco-plastico.
Il problema che il tecnologo di produzione si trova ad affrontare è quello di definire le diverse fasi di stampaggio per trasformare il disegno del pezzo finito nel disegno del grezzo e della
cavità degli stampi, con un procedimento che segue diverse fasi di progetto. Lo stampaggio prevede un ciclo di lavoro molto
complesso, con aspetti che richiedono competenza scientifica
ed esperienza per la definizione delle diverse fasi in maniera
corretta sia per l’ottenimento di un corretto manufatto esente
da difetti, sia nella scelta della soluzione più economica.
Lo studio condotto si prefigge l’obiettivo di dare un contributo significativo allo sviluppo di tecniche per la progettazione
e l’ottimizzazione dei processi di lavorazione per deformazione di acciai. L’intero progetto ha lo scopo di poter migliorare
il controllo del processo di deformazione, l’analisi delle difettosità, delle forze e delle sollecitazioni a fatica degli stampi
su base ripetibile in ambiente produttivo della moderna realtà industriale.
Il componente forgiato preso in esame è una forcella, organo
meccanico di collegamento atto alla trasmissione di forze statiche e dinamiche, prodotto in tre passaggi: Preformatura,
Abbozzatura e Finitura. Nella prima parte dell’attività si è esaminato lo stato dell’arte del processo di produzione del particolare preso in considerazione, conducendo studio FEM del processo reale: studio della parte “teorica” di processo, introduzione
ed approfondimento delle basi della fisica, meccanica e strutturale per comprendere le dinamiche della deformazione plastica a
caldo di un materiale metallico, le metodologie e le operazioni
che li caratterizzano.
Nell’ultima fase di stampaggio, Finitura, dopo un numero esiguo
di prodotti, si riscontra nella realtà produttiva il fenomeno di
rottura dello stampo superiore in una regione ben localizzata di
concentrazione degli sforzi. Lo studio si è focalizzato sull’analisi di tale fenomeno, il quale inficiava la produttività reale del
processo, ponendosi l’obiettivo di minimizzare il carico pressa
necessario alla deformazione, e ottimizzare il binomio processo/prodotto variando le condizioni a contorno, nel pieno rispetto dei vincoli di completo riempimento e nulla difettologia sul
forgiato finale.
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34 - Newsletter EnginSoft Year 9 n°4
L’ottimizzazione è stata condotta sull’intero processo, concatenando le diverse operazioni di forgiatura intimamente accoppiate con l’evoluzione termica del componente in deformazione e
nelle fasi intermedie di passaggio da una all’altra operazione. I
risultati hanno permesso di correlare la variazione dei principali parametri di processo ai benefici ottenuti: risparmio di materiale (benefit economico) e diminuzione di onerosità di processo (benefit energetico-economico-ecologico).
Nella parte finale dello studio, ci si è concentrati nell’analisi di
sollecitazione degli stampi con approccio disaccoppiato. Si è testato attraverso analisi FEM, dapprima la riproduzione di sollecitazione e plasticizzazione dello stampo nelle aree di innesco rottura, con verifica del numero di cicli e previsione di vita utile
prima di arrivare a rottura duttile; in un secondo momento si è
testato come le condizioni di ottimo apportassero significative
migliorie anche al fenomeno di “rottura a fatica”.
Processo di deformazione plastica a caldo
Le lavorazioni per deformazioni plastica di materiali metallici
hanno origini lontanissime nella storia della tecnica. Sottoposto
all’azione di forze esterne tramite presse o magli, il materiale varia permanentemente la sua forma originale; tale trasformazione
avviene allo stato solido-viscoso. I processi di lavorazione per
deformazione possono essere suddivisi in:
• primari, utilizzando materiale da fusione e ottenendo semilavorati commerciali destinati ad uso diretto o ad ulteriori
deformazioni;
• secondari, da prodotti di deformazione primaria si ottengono manufatti di forma e dimensioni finite.
stampaggio a caldo è una tipica lavorazione per produzione di
grande serie. Di contro lo svantaggio è quello di necessitare
di energia per il riscaldo, favorire l’ossidazione del metallo ed
inoltre risulta difficile prevedere la precisione dimensionale
ottenibile.
La billetta iniziale è uno spezzone quadro (sezione 120x120 mm,
raccordo R20, lunghezza 327 mm, peso 36 kg) proveniente da
deformazione primaria, in C25/1.0406, il volume della billetta
Fig. 2 - Bielletta iniziale in C25. Forcella Forgiata - Prodotto Finito
tiene conto anche della maggiorazione della percentuale di perdita di materiale per ossidazione (calo termico); mentre il prodotto finale di forgiatura è una forcella di trasmissione meccanica (Fig.2).
Lo spezzone di acciaio viene riscaldato in forno con lo scopo di
arrivare alla temperatura idonea di stampaggio, che deve essere
la più alta possibile, rimanendo tuttavia distante dal punto di
La corretta progettazione dello stampaggio deve assicurare un
fusione per evitare liquefazioni e bruciature di materiale: circa
corretto e completo riempimento degli stampi, studiandone i parametri ed i fattori che lo influenzano:
1250°C. Tale temperatura deve essere maggiore di quella critica
di transizione vetrosa per poter sfruttare la migliore deformabi• deformabilità e resistenza allo scorrimento;
lità, il materiale a tale temperatura ha una caratteristica elasto• uso di lubrificanti;
• temperatura della parte deformabile e degli stampi;
visco-plastica. Il tempo che intercorre dall’uscita forno al primo
step di deformazione provoca una caduta termica della superfi• forma del pezzo finale;
• calcolo della forza necessaria.
cie della billetta che scambia calore con l’aria circostante (minimizzazione del tempo di fuori forno).
Nella maggior parte dei casi di processo di stampaggio è necesI processi di deformazione a caldo avvengono ad una temperasario deformare progressivamente il materiale di partenza, per
tura maggiore della temperatura critica di ricristallizzazione, i
garantire un riempimento accurato degli stampi e per ottenere
vantaggi di tale metodo sono sia le minori forze e potenze riuna valida distribuzione delle fibre all’interno del prodotto finachieste, sia la possibilità di indurre grandi deformazioni e l’ottele. La non uniformità di deformazione influenza negativamente
nimento di forme anche complesse, grazie alla maggior duttilità
le caratteristiche meccaniche finali dello stampato, per cui eledei metalli alle alte temperature (Fig1). Limitando le forze nevata cura va profusa nello studio dell’intero processo. Spesso si
cessarie e sfruttando la migliore deformabilità del materiale, lo
necessita quindi di sbozzati intermedi la cui
forma e dimensione è mediata tra lo spezzone iniziale e lo stampato finale, attraverso stampi sbozzatori, con caratteristiche simili a quelli finitori, possono essere ottenuti tali sbozzati.
Il processo industriale reale è uno stampaggio in tre fasi deformative: Preforma,
Abbozzatura e Finitura. Tutte e tre le fasi di
Fig. 1 - Deformazione Plastica di un Materiale metallico e proprietà. Effetti dell’incrudimento sulle
stampaggio sono ottenute dall’azione della
caratteristiche meccaniche. Effetti della temperatura sulle caratteristiche meccaniche di un materiale
Pressa Meccanica (Fig.3) che impartisce il
metallico.
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Newsletter EnginSoft Year 9 n°4 -
Fig. 3 - Pressa Meccanica. Sx Schema di una pressa meccanica ad eccentrico.
Dx Cinematismo Biella-Manovella
cinematismo. La pressa meccanica utilizzata nel processo industriale analizzato ha le seguenti caratteristiche cinematiche:
Raggio di manovella = 100 mm, Velocità di rotazione = 55 rpm,
Rapporto (raggio di manovella)/(Lunghezza di biella) =
0.14285. L’organo mobile con un moto alternativo esercita una
forza sul materiale da deformare, durante la sua corsa attiva fino al Punto Morto Inferiore. In tale punto di lavoro la forza disponibile tende all’infinito, ma i costruttori limitano con dispositivi di protezione, la forza massima esprimibile in deformazione ad un valore detto nominale. La forza richiesta dal processo
di deformazione deve essere sempre inferiore a quella disponibile. La prima deformazione è in gergo una tipica ricalcatura dello spezzone per discagliatura successiva al riscaldamento in forno ed un miglior posizionamento all’interno della sagoma della
stazione di deformazione successiva. La billetta deformata viene
collocata sullo stampo inferiore di Abbozzatura, in modo da poter coprire il più possibile il vuoto ricavato nello stampo, e quindi la figura da dover ottenere. In questa seconda fase, al contrario di quella di Ricalcatura in cui gli stampi sono piani, il materiale deve riempire il vuoto fra gli stampi, e quindi deve scorrere sulla loro superficie sotto l’azione della Pressa Meccanica che
impartisce il cinematismo.
La fase di Abbozzatura presenta un posizionamento della billetta ricalcata che non è univoco, infatti non sono state predisposte sullo Stampo Inferiore delle staffe di appoggio e trattenimento della billetta deformata proveniente dalla fase di
Ricalcatura. E’ stata fatta la scelta di posizionare la billetta in
modo che la superficie superiore coincidesse con la fine della superficie cava dello stampo inferiore, il robot antropomorfo ha un
errore trascurabile nella determinazione di tale posizione.
A fine deformazione l’abbozzato ha una forma moto simile a
quella del prodotto finito, ma, in questa fase di deformazione,
naturalmente, non viene richiesto né un riempimento ottimale
né l’assenza di difetti, quali ripieghe.
L’abbozzato viene tolto dalla cavità degli stampi tramite l’ausilio di un apposito estrattore, il manipolatore lo posiziona nella
cavità dello stampo finitore; avendo una forma molto simile la
figura riesce ad auto centrarsi per gravità nella posizione corretta desiderata. Sotto l’azione della stessa Pressa Meccanica, il
manufatto viene portato a dimensioni nominali di progetto, il fi-
35
nito rispetta la condizione di completo riempimento degli stampi, non presenta difetti nelle parti in cui non possono essere tollerati nella qualità di produzione ed ha un’altezza di bava pari a
5 mm. Il finito di stampaggio verrà successivamente sottoposto
al processo di eliminazione della bava, sempre in linea quindi a
caldo, trattamento termico, pulitura superficiale, coniatura e
controllo prima di essere inviato alle macchine utensili per le lavorazioni per asportazione di truciolo.
Sebbene il processo non presenta difetti di stampaggio, si nota
prima di tutto che il materiale iniziale utilizzato per lo spezzone di billetta potrebbe essere minimizzato, visto il peso rilevante occupato dalla bava; secondariamente, in ordine di tempo ma
non di importanza, si evidenzia come dopo un numero di cicli
esiguo per una larga produzione di serie si arrivi alla rottura degli stampi.
Studio di Processo attraverso Analisi FEM
Lo studio del processo reale è stato condotto attraverso codice numerico che permettesse dapprima di poter definire tutti
i parametri di processo e poi poterne studiare, secondo la loro variazione, le influenze nel processo stesso. E’ stato implementato l’intero ciclo di stampaggio partendo dalla billetta
fredda dimensionata secondo progetto reale ed il suo inserimento in forno, fino alla completa deformazione in fase di
Finitura; nel Codice Numerico è stato implemento un chaining
delle varie fasi di stampaggio, in modo da poter automaticamente far calcolare l’intera sequenza e seguire in essa l’evoluzione del comportamento del materiale in deformazione, con
particolare attenzione alla termica del processo, alle tensioni
ed alle sollecitazioni.
La modellazione del processo nelle sue diverse fasi prevede non
solo quella geometrica, di facile implementazione con i moderni CAD, ma anche quella fisica, in cui il materiale, la termica ed
i contatti rivestono ruoli primari. Il materiale della parte deformabile è descritto tramite il modello di Hansel Spittel (Fig.4),
mentre gli stampi in ogni fase di stampaggio sono considerati
come elementi indeformabili, infinitamente rigidi ed a temperatura costante (temperatura a regime).
Lo scambio termico è definito in modo da descrivere il fenomeno sia quando la billetta è a contatto con gli stampi (αT =
2.0e+04 W/m²°K; effus = 1.176362e+04), sia quando non lo è e
quindi scambia calore con l’ambiente circostante (αText =
10.0e+00 mW/mm/°C); per la velocità di esecuzione di proces-
Fig. 4 - Coefficienti del modello di Hansel Spittel del C25/ 1.0406
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36 - Newsletter EnginSoft Year 9 n°4
so di deformazione alla pressa meccanica, ci si
aspetta che l’influenza dello scambio termico
sia di bassa rilevanza tra i diversi parametri in
gioco. Attraverso la Legge di Coulomb-Tresca,
l’attrito è stato definito in maniera conforme
alla realtà dei diversi setup delle fasi di processo reale; in fase di abbozzatura non viene interposto alcun lubrificante, mentre le fasi successive di abbozzatura e finitura hanno una lubrifica spinta per poter far scorrere il materia- Fig. 6 - Lo stampo superiore, nella fase di finitura, presenta rottura dopo un numero esiguo di
le in deformazione nelle parti vuote dello stampate, rispetto alla totale produzione, concentrata in una determinata zona ben visibile.
Materiale stampo: X37CrMoV5 H11 bonificato 42 HRC.
stampo. E’ stato quindi implementato un coefficiente alto di attrito in fase di abbozzatura (m = 0.6; µ = 0.3)
stampo in fase di finitura (quello che nella realtà subiva la rote più basso in fase di abbozzatura e finitura (m = 0.1; µ= 0.05)
tura dopo un esiguo numero di cicli di stampaggio). A tale scorispettando l’omogeneità di distribuzione dei lubrificanti che
po si è adottato un modello dello Stampo di Finitura deformabinella realtà è ottenuta in maniera automatizzata.
le, sia elasticamente che elasto-plasticamente, ed è stato calcoTutte le fasi di stampaggio (Fig.5) sono ottenute mediante la
lato il grado di sollecitazione e deformazione elasto-plastica traperfetta implementazione cinematica del manovellismo della
mite la proiezione su di esso delle forze ricavate dal modello a
pressa meccanica precedentemente descritto. Tra una fase di
stampi rigidi. Dall’analisi delle sollecitazioni dello stampo dustampaggio e quella successiva è stato implementato il calcorante la fase di finitura si evidenzia, nella parte finale di deforlo della caduta termica in aria per un tempo necessario alla
mazione, la concentrazione di elevati valori della tensione prinmovimentazione reale della billetta, ottenendo quindi una
cipale (1srPrincipalStressTensor) in quella che nella realtà appamappa della temperatura più adiacente alle condizioni reali di
re come la linea di innesco della frattura (Fig.6); se positivo, il
stampaggio.
1srPrincipalStressTensor rappresenta il massimo sforzo di trazione, ed il superamento di valori critici è il primo fattore di rottuTutte le fasi di stampaggio (Fig.5) sono ottenute mediante la
ra fragile. I valori pur non superando quelli critici hanno caratperfetta implementazione cinematica del manovellismo della
tere ciclico, per cui la fenomenologia da indagare è quella di rotpressa meccanica precedentemente descritto. Tra una fase di
tura per fatica oligociclica.
stampaggio e quella successiva è stato implementato il calcoLo stampo superiore, nella fase di finitura, presenta rottura dolo della caduta termica in aria per un tempo necessario alla
po un numero esiguo di stampate, rispetto alla totale produziomovimentazione reale della billetta, ottenendo quindi una
ne, concentrata in una determinata zona ben visibile. Il materiamappa della temperatura più adiacente alle condizioni reali di
le stampo è X37CrMoV5 H11 bonificato 42 HRC.
stampaggio. I risultati ottenuti dal calcolo FEM, sono stati confrontati con quelli reali di stampaggio validando la scelta dei nuFenomeno di Rottura per Fatica Oligociclica
merosi parametri di processo assunti nelle varie fasi. La forma fiLo studio condotto ha permesso di legare la fatica ai fenomeni
nale dello stampato, la sua mappa termica e le forze di stampagdi micro-deformazioni plastiche cicliche locali indotte dal ciclo
gio calcolate sono identiche a quelle ottenute nella realtà, così
di sollecitazioni, il cui valore di sforzo localmente può superare
come i difetti di ripieghe sono collocati negli stessi punti, cioè
il carico di snervamento anche se il carico macroscopico esterno
in bava e nelle zone di lavorazione meccanica successiva.
rimane sempre al di sotto di esso. Il danneggiamento per fatica
Tale studio preliminare condotto ha avuto l’obiettivo di modelprocede attraverso un primo assestamento microstrutturale, che
lare le condizioni reali di processo, fino a poter valutare il grastabilizza il ciclo di isteresi plastica dello stampo metallico e, di
do di sollecitazione degli stampi durante il processo deformaticonseguenza, stabilizza alcune caratteristiche meccaniche e fisivo. Gli stampi, come precedentemente affermato, sono stati asche dello stesso. Si generano microintagli dovuti a slittamenti
sunti come infinitamente rigidi ed indeformabili, per cui la se"disordinati" dei piani cristallini del metallo che nella successiconda fase di studio, partendo dai risultati validati, ha valutato,
va fase di nucleazione andranno a costituire l'innesco del dancon approccio disaccoppiato, lo stato di sollecitazione dello
neggiamento per fatica. Gli sforzi risultano amplificati per effetto d'intaglio cosicché facilmente il materiale in
quel punto cede e si formano delle microcricche. Queste tendono a riunirsi andando a formare la cricca vera e propria, che si considera
ormai nucleata quando raggiunge la profondità
di circa 0,1 mm. Dopo la nucleazione della
cricca, la sua propagazione avviene in maniera
fragile e in senso perpendicolare a quello del
massimo sforzo. L'avanzare della cricca porta
ad una progressiva diminuzione di sezione resistente: quando questa diventa inferiore alla
Fig. 5 - Risultati delle simulazioni di stampaggio
Case Histories
Newsletter EnginSoft Year 9 n°4 -
37
sezione critica, si ha la frattura finale di
schianto per sovraccarico (statico). La resistenza a fatica degli stampi è frutto della combinazione di stress meccanici e termici, in
Fig.7 è rappresentata qualitativamente la metodologia di Valutazione composita delle componenti meccaniche e termiche della deformazione, ciò ha permesso di stimare la vita utile
dello stampo studiandone la sollecitazione ed i
suoi effetti di fatica (Materiale stampo:
X37CrMoV5 H11 bonificato 42 HRC). Al fine di
valutare eventuali variazioni termiche sullo
stampo, sono state analizzate le temperature
della billetta in corrispondenza della zona
maggiormente sollecitata ed i fattori metallur- Fig. 7 - Valutazione composita delle componenti meccaniche e termiche della deformazione
gici di influenza
Il limite di fatica si lega inevitabilmente:
Con algoritmi di tipo MAES (Meta-model Assisted Evolution
• alla tensione di rottura Rm ed ai fattori che la modificano;
Strategies MAES) si utilizza una valutazione delle minimizzazio• fattori meccanici legati all'esercizio e al dimensionamento
ni e dei vincoli per selezionare gli individui che si vogliono efdel prodotto metallico;
fettivamente calcolare. Ci sono differenti tecniche per costruir• la finitura superficiale e la corrosione.
lo e il tempo di valutazione usando il Meta Model varia in funzione della tecnica scelta ma in tutti i casi esso è molto più breAnche la forma del pezzo ha importanza sulla vita a fatica, ogni
ve della semplice analisi FEM ed è quindi possibile incrementalieve variazione di sezione, determinando delle concentrazioni di
re la dimensione della popolazione mantenendo il tempo per
tensioni e localizzando le deformazioni, agisce sempre nel senl’ottimizzazione pressoché costante.
so di una netta diminuzione del limite di fatica, per questo hanno un'azione dannosa fori, intagli e spigoli vivi.
Ottimizzazione di Processo
Lo studio di lavorazione per deformazione fin qui descritto è stato propedeutico alla ricerca del miglior setup per l’individuazione dell’ottimo binomio prodotto/processo ed all’analisi avanzata dell’influenza dei vari parametri. Si è proposto quindi l’impiego di un approccio statistico da correlare alla fase di raccolta dati che permettesse alla progettazione di raggiungere i seguenti
risultati:
• riduzione dei tempi di sviluppo dei processi;
• uso più efficiente delle risorse;
• maggiore affidabilità dei processi.
Nell'ambiente industriale la complessità dei fenomeni impedisce
il pieno controllo dei fattori sotto indagine e una conoscenza
teorica completa: ciò significa che non sempre è nota a priori la
relazione di causa-effetto tra i fattori che influiscono sul processo in esame e le variabili da ottimizzare, una delle tecniche di
progettazione per massimizzare le informazioni derivanti da dati sperimentali è il Design of Experiments (DOE), metodo che
consta di due fasi principali:
• fase di screening: identificazione dei fattori significativi e
loro correlazione;
• fase di ottimizzazione: identificazione della risposta.
La scelta dell’algoritmo nel codice numerico utilizzato è di tipo
generico:
• iniziare da una popolazione: un numero predefinito di individui che può essere definito prima generazione;
• valutarli (calcolarli e valutare minimizzazioni e vincoli);
• selezionare i migliori, riprodurli e creare una nuova generazione.
Fig. 8 - Scelta casuale della popolazione iniziale rispetto al numero
dei parametri
Tali algoritmi presentano la limitazione di richiedere diverse
centinaia di valutazioni e di simulazioni complete; la Strategia
di Evoluzione Assistita da Meta-Model (MAES) rende possibile ridurre considerevolmente il numero dei calcoli effettivi. Si possono ottenere buoni risultati all’interno di poche decine di calcoli e grazie al calcolo parallelo, le analisi/simulazioni possono
essere condotte allo stesso tempo riducendo il tempo di ottimizzazione. Gli algoritmi evolutivi (ES) consistono tipicamente di
tre operazioni: selezione, ricombinazione e mutazione, per ridurre il numero di valutazione di funzioni.
Lo studio di ottimizzazione condotto sul processo deformativo
preso in considerazione può essere riassunto nella scelta dei target della funzione Obiettivo da minimizzare, parametri di variazione e vincoli da rispettare:
Target Obiettivo di ottimizzazione
• Minimizzazione volume iniziale billetta.
• Minimizzazione carico pressa durante la fase di abbozzatura.
• Minimizzazione carico pressa durante la fase di finitura.
Vincoli di ottimizzazione
• Completo riempimento stampi in fase di finitura.
• Assenza di difetti di stampaggio in fase di finitura.
Case Histories
38 - Newsletter EnginSoft Year 9 n°4
Analizzando non solo i setup efficaci, ma l’intera popolazione di parametri scelti nei ranges
di interesse, si sono valutate le influenze che
la variazione di parametri scelti hanno sul carico degli stampi in fase di abbozzatura e soprattutto di finitura, visto che questa è la fase in cui la rottura degli stampi avviene dopo
un numero esiguo di cicli di stampaggio.
Fig. 9 - Intera popolazione di individui di ottimizzazione.
La variazione di massa della billetta iniziale
riflette una variabilità estremamente accentuata della forza di stampaggio nella fase di
abbozzatura, mentre nella fase di finitura, così come ci si aspetta dalla configurazione della fase di stampaggio, presenta una più modesta minimizzazione. Il grafico di Fig.9 riporta
la totalità dei casi analizzati.
Nel grafico di Fig.10 si riporta l’andamento
Fig. 10 - Individui che soddisfano i vincoli
della forza di stampaggio in funzione della
massa iniziale di billetta, solo per i 21 casi (su
40) soddisfacenti il vincolo di completo riempimento e nessuna ripiega in finitura, si evidenzia come la ricerca dell’ottimo, pur spaziando su tutto il range, si concentra nella zona di minimo carico e minimo volume.
Nel grafico di Fig.11 si riporta l’andamento
della forza di stampaggio in funzione del posizionamento della billetta in fase di abbozzatura rispetto alla posizione originaria. Si nota
Fig. 11 - Influenza della variazione di posizione della billetta in fase di abbozzatura sulla forza di
stampaggio nella fase di abbozzatura e sulla fase di finitura. Individui che soddisfano i vincoli
come la forza di stampaggio risulta essere non
correlabile alla variabile posizionamento, infatti la billetta ricalcata posizionata sullo stampo inferiore di
Parametri di ottimizzazione
abbozzatura tende sempre a “scivolare” verso la parete di ap• Lunghezza billetta = min 94% lunghezza originale, corripoggio perdendo la variazione di posizionamento. I risultati dispondente a una riduzione massima di peso di 2 kg.
mostrano come la convergenza dell’algoritmo MAES porti ad una
• Posizionamento billetta: traslazione massima 15,5 mm lungo
soluzione soddisfacente in cui il vincolo di riempimento è sodasse X (Xg = -2mm).
disfatto dopo la prima generazione dell’algoritmo, e le generazioni successive permettono di minimizzare l’acciaio impiegato
L’algoritmo MAES è stato organizzato con una popolazione di 10
e di minimizzare la forza impiegata nelle fasi di Abbozzatura in
famiglie di 4 individui ciascuna, per un totale di 40 casi di commaniera significativa e di Finitura in misura minore (Fig12). In
binazioni. Ogni combinazione prevede lo sviluppo di tutto il proquesta fase gli stampi accolgono tutto l’abbozzato andando a
cesso di forgiatura e quindi le varie fasi di Ricalcatura,
contatto con lo stesso direttamente sulla bava, il materiale in
Posizionamento billetta ricalcata nella fase di Abbozzatura,
deformazione è costretto a riempire, ma non può fluire verso
Abbozzatura e Finitura, per un totale di 160 simulazioni complel’esterno. Le cavità degli stampi sono già completamente riemte di forgiatura.
pite quando al cinematismo mancano ancora 3,5 mm di corsa,
durante la quale il carico della pressa non aumenta, vista la suRisultati
perficie ormai tutta in presa, bensì aumentano gli sforzi di traL’interfaccia grafica di visualizzazione dei risultati del codice
zione massima sugli stampi nella sezione in cui si innesca la
numerico utilizzato è estremamente intuitiva, attraverso rancricca. Tale ultimo risultato, unitamente alla deformazione e
king dei diversi casi, permette di valutare immediatamente la
riempimento visualizzabile step by step, ha posto le basi di imsoluzione migliore. Il ranking viene organizzato in maniera auplementazione di ottimizzazione successiva: partendo dalla sotomatica mediante una funzione di costo, che valuta il rispetto
luzione migliore di prima ipotesi ed indagando un range di vadei vincoli inseriti ed il risultato ottenuto in termini di miniriazione del volume iniziale della billeta che minimizzasse ultemizzazioni richieste. Analizzando i numerevoli risultati prodotriormente il risultato ottenuto, ed aggiungendo ad essi una difti, automaticamente si riesce a distinguere, in verde, i setup che
ferente geometria del preformato di Abbozzatura.
hanno rispettato i vincoli di processo imposti, cioè il completo
La nuova fase di abbozzatura studiata prevede un prodotto pririempimento e l’assenza di difetti nei volumi ove ciò è richievo di bava, la forma è molto meno vicina al finito di stampagsto, dalle soluzioni in arancione in cui le impostazioni non sogio, quindi più intermedia. Questa soluzione registra una noteno sufficienti a soddisfare tali vincoli.
Case Histories
Newsletter EnginSoft Year 9 n°4 -
vole diminuzione del carico pressa in fase di
Abbozzatura, ma anche in fase di Finitura. La
modifica al processo, dopo l’analisi di ottimizzazione e le valutazioni delle influenze dei parametri, ha permesso una distribuzione più
omogenea degli sforzi e delle deformazioni
nelle diverse fasi di processo, studiando una
preformatura che permettesse di utilizzare ancor meno materiale (Fig.13), garantendo un
completo riempimento ed assenza di difetti
nel prodotto finale. Per minimizzare il rischio
di rottura duttile nello stampo di finitura è
stato accentuato il raggio di raccordo nel punto di innesco (R1) per non favorire la concentrazione localizzata degli sforzi di trazione, gli
altri parametri geometrici (R2 ed L1) non sono significativi, così come la temperatura iniziale (T1) dello stampo perché bassa, mentre
è da monitorare la temperatura finale (T2)
perché ad un suo aumento corrisponde una
maggiore deformabilità del materiale fino a
valori critici.
39
Fig. 12 - a) Diverso posizionamento in fase di Abbozzatura. b) Contatti e riempimento in Finitura del
Caso Iniz. e del Caso Ott. c) Carico in Abbozzatura per il Caso Iniz. e per il Caso Ott. d) Carico in
Finitura per il Caso Iniz. e per il Caso Ott.
Conclusioni
Lo studio condotto sul processo di stampaggio
a caldo di acciaio si è incentrato su un’analisi
numerico sperimentale, i cui obiettivi principali sono stati l’ottimizzazione del processo
prendendo in esame le variazioni dei parametri nei range di analisi; tale approccio ha consentito di dare rigore a quelle soluzioni nel
processo in esame che discendevano dalla
Fig. 13 - Influenza dei parametri geometrici dello stampo su resistenza a Fatica Termo Meccanica.
semplice esperienza degli operatori ed ha con- Risparmio di materiale dopo due studi di ottimizzazione di processo.
sentito l’ottimizzazione del ciclo di produzione
di un componente di geometria complessa.
La modellazione numerica, analizzando i fattori più influenti, ha
L’ottimizzazione multi-obiettivo è stata condotta sull’intero prodato l’opportunità di proporre ulteriore minimizzazione del macesso ed i risultati hanno permesso di correlare i principali pateriale e suggerire variazioni delle geometrie degli stampi al firametri di processo ai benefici desiderati ed ottenuti: risparmio
ne di avere un prodotto che in fase di finitura richieda una midi materiale (benefit economico) e diminuzione di onerosità di
nore drasticità di applicazione del carico pressa, intimamente
processo (benefit energetico-economico-ecologico):
collegato al fenomeno di rottura degli stampi in quella
• Ottimizzazione del materiale:
faseL’ottima rispondenza nel confronto numerico sperimentale
• -27% di risparmio di materiale scartato dopo Prima
ha consentito di desumere l’affidabilità dei risultati forniti, il
Ottimizzazione
che potrà portare alla possibilità di migliorare cicli già esisten• -49% di risparmio di materiale scartato
ti, ma anche di progettare nuovi componenti e cicli di produziodopo Seconda Ottimizzazione
ne con vantaggi in termini di tempo ed economici. La sperimen• Ottimizzazione del carico pressa pari a:
tazione virtuale non è più considerata come una fase di test vol• 1399 T fase di abbozzatura: - 24 % dopo Prima
ta a verificare se l'implementazione pratica di un nuovo procesOttimizzazione
so/prodotto risponde effettivamente agli obiettivi fissati in fa• 1200 T fase di abbozzatura: - 31,4 % dopo
se di progettazione. Essa apporta valore aggiunto se pensata
Seconda Ottimizzazione
non solo come conferma di quanto previsto ma soprattutto co• 1500 T fase di finitura: - 4,2 % dopo Prima
me potenziale fonte di opportunità di miglioramenti non intuiOttimizzazione
bili a priori.
• 1400 T fase di abbozzatura: - 10,4 % dopo
A.Pallara - EnginSoft,
Seconda Ottimizzazione
Y.Cogo, S. Mazzoleni - Feat Group
• Assenza di difetti e di ripieghe nella soluzione ottimizzata.
Per ulteriori informazioni:
• Completo riempimento in fase di finitura della soluzione
Marcello Gabrielli, EnginSoft
ottimizzata.
[email protected]
Case Histories
40 - Newsletter EnginSoft Year 9 n°4
Nella International CAE Conference si
è tenuto il Meeting Italiano degli
utilizzatori di Forge
Il 23 ottobre, all'interno della International CAE Conference, il
centro di competenza simulazione di processo - forgiatura di
Enginsoft ha voluto invitare tutti gli utilizzatori del software
Forge/ColdForm per una sessione di aggiornamento sui prodotti.
Transvalor, la casa produttrice del software, ha voluto essere
presente con il dott. Jean Fourniols e l'ing. Laetitia Pegie, che
hanno illustrato la roadmap di sviluppo dei prodotti e suggerito il "modus operandi" di utilizzo. L'incontro, al quale hanno assisitito una quarantina di persone, ha visto protagonisti anche
alcuni utenti, che hanno presentato il proprio lavoro: l'ing.
Sartori di Muraro-Stipaf (nella foto) ha raccontato come intere
linee di laminazione circolare vengono progettate in virtuale,
tenendo conto di tutte le fasi e della metallurgia del materiale,
l'ing. Pallara di Enginsoft ha mostrato un caso pratico di ottimizzazione di una forcella in acciaio stampata a caldo da FEAT
Group, il dott. Michele Francesco Novella del DII - Università di
Padova ha mostrato come è possibile prevedere l'evento di frattura duttile nello stampaggio a freddo ed infine l'ing Inaki Perez
di Tecnalia ha illustrato come nei laboratori spagnoli si utilizzano questi strumenti per simulare il complesso processo di rotary forging. I partecipanti hanno potuto apprendere informazioni utili per l'uso quotidiano di Forge e ColdForm, ma soprattutto conoscersi e scambiarsi consigli su come far rendere al
meglio questi strumenti.
Il centro di competenza di
Enginsoft sulla forgiatura
(in foto da sinistra a destra
l'ing. Andrea Pallara, l'ing.
Marcello Gabrielli e l'ing.
Federico Fracasso) ha nelle
pause approfondito tematiche individuali, con il
supporto di Transvalor.
Appuntamento per tutti all'edizione numero 10 dell'Italian
Forge Users' Meeting, nel 2013.
Per ulteriori informazioni:
Marcello Gabrielli, EnginSoft
[email protected]
Events
EnginSoft al Convegno AIM di Trento
Dal 7 al 9 novembre si è svolto a Trento il 34° Convegno
Nazionale di A.I.M. (Associazione Italiana Metallurgia),
che ha visto la partecipazione di oltre 300 persone
provenienti sia dal mondo universitario e della ricerca, che
dal mondo industriale.
Enginsoft ha voluto essere presente a questo importante
evento in una duplice veste, come sponsor e portando dei
contributi scientifici
nelle sessioni tecniche.
E' stato quindi allestito
uno stand, dove si sono
alternati
Marcello
Gabrielli, Piero Parona e
Giampietro Scarpa, che
hanno dato informazioni in merito alle
diverse attività di
simulazione e di ottimizzazione che Enginsoft è in grado
di affrontare. Per le sessioni tecniche, Marcello Gabrielli
ha presentato nella sessione Acciaieria un lavoro di
ottimizzazione condotto in collaborazione con FEAT Group
dal titolo "Studio di fattibilità produttiva attraverso
simulazione numerica", mentre Giampietro Scarpa ha
illustrato nella sessione Pressocolata, che ha visto come
chairman Piero Parona (Presidente del Centro di Studi
Pressocolata di AIM) il lavoro "Analisi delle difettologie
nel processo di pressocolata: contributo della simulazione
numerica".
Enginsoft è stata invitata a tenere una lezione
al Corso di "Siderurgia e fonderia" del 5° anno Corso di Laurea Magistrale in Ingegneria dei
Materiali.
Il 20 novembre l'ing.
Marcello Gabrielli è stato invitato dal prof.
Giovanni Staffelini a tenere una lezione agli
studenti del 5° anno di
Laurea Magistrale dell'Università di Trento - Facoltà di
Ingegneria del Materali. La lezione ha riguardato una panoramica dei processi di solidificazione in lingottiera e di
colata continua, affrontati dal punto di vista della simulazione numerica. Il docente ha illustrato quanto sia difficile definire un materiale per questo tipo di simulazioni, per poter ottenere dei risultati prossimi alla realtà
produttiva. La presentazione di alcuni casi reali ha stimolato la discussione in aula e l'interesse dei ragazzi,
che hanno visto applicate nella pratica le nozioni apprese durante il loro percorso di studi. Sono emersi anche alcuni temi di interesse, che saranno approfonditi in prossimi lavori di tesi, nei quali la simulazione potrà avere un
ruolo importante.
Newsletter EnginSoft Year 9 n°4 -
41
Multidisciplinary optimization for a IEEE 1902.1
“RuBee” tag integrated in a fiber-reinforced
composite structure through the “RuBeeCOMP”
Numerical Platform
INTRODUCTION TO THE RUBEECOMP PROJECT
THE OBJECTIVES
RuBeeCOMP is a research project co-funded by the Regione
Toscana (Italy) in the frame of the POR CReO funding program.
which were installed into the vehicle as illustrated in the
concept picture in Figure 1, enable these measurements.
The main objective of the RuBeeCOMP project is to define the
best possible configuration for the composite structure and
the wireless tag. For the specific work and the required data,
a numerical platform was developed that coordinates both, the
geometrical/functional parameters of the tag and the
composite laminate. The technological platform was developed
in order to integrate the data obtained during the project’s
preliminary phases and from the parametric FE models, to
achieve the best configuration for the executive design.
Fig. 1 - Simulation of a submarine mission for the inspection
of the seabed
The aim of the project is to study, test and assess materials,
systems, technologies as well as design methodologies for the
manufacturing of composite material components. Wireless
communication systems able to operate in radiofrequency
unfriendly environments, such as oil or water, are also
included in the study and project activities.
At first, the composite demonstrator with the wireless
communication system has been installed into a submarine
vehicle, which is able to explore the seabed and to monitor
the submarine environment by performing optical and sound
surveys, and physical and chemical analyses. Suitable sensors
Fig. 2 - 3-point-bending test realized on composite virgin
and aged specimens
Fig. 3 - Environment tests on composite specimens containing the wireless
tag (a) and electromagnetic setup of the communication systems (b)
Research & Technology Transfer
42 - Newsletter EnginSoft Year 9 n°4
The five main Project “Work
Packages” completed during the last
two years allow to define the
optimum
solution
for
the
technological demonstrator realized,
guaranteeing the highest achievable
level of performances in terms of
structural and electromagnetic
response.
Fig. 5 - Structural FE model developed in ANSYS Mechanical and ANSYS ACP environments
EXPERIMENTAL ANALYSIS
Once the functional requirements of
the wireless tag and the whole
vehicle are defined on the base of
mission length, depth and velocity
expected and amount of information
collected, a preliminary study of the
vehicle geometry is carried out, of Fig. 6 – Draping and Flat Wrap analysis realized in ANSYS ACP on the rear double-curved surfaces
the
candidate
wireless
communication systems and of a set of candidate composite
laminate, several full parametric models are realized using an
materials through a rich experimental campaign. On the
hybrid approach (numerical and empirical) verified within
composite materials chosen, a set of physical and mechanical
ANSYS Maxwell and ANSYS HFSS simulation environments. The
tests are realized on virgin and aged specimens, with or
main variables evaluated for the electromagnetic issue are
without the wireless tag.
magnetic field and inductance, functions used hereinafter in
the optimization environment to select the best allowed
configuration. The first model represents the prototype of an
antenna with a 42mm radius multi-turn coil made of 33 loops
of a copper wire (section radius equal to 0.25mm). The second
model is a multi-turn printed loop on a 0.8mm thick FR4
laminate. The CPW fed antenna is made of 16 properly
distanced 0.6mm wide microstrip copper line turns. The
background scenario was modeled by imposing radiation
boundaries to the problem region in order to simulate free
emission into space. In the operational environment, the
latter could be a lossy and/or conductive media like sea water
Fig. 4 - Electromagnetic F models developed in ANSYS HFSS simulation
or oil and it should be consequently modeled with the
environment
correspondent electric characteristics.
To evaluate the established communication degree, two
different multi-turn tags are tested: a 33-turn copper wire coil
STRUCTURAL MODELS
and a multi-turn microstrip coil. All the composite specimens
The numerical platform developed for the RuBeeCOMP research
are tested through thermal and moisture loads, structural
project allows to maximize the structural and electromagnetic
loads (time-increasing distributed pressure, bending),
performances through suitable optimization tools, analyzing
vibrations and shockproof, monitoring internal and external
custom FE models built in ANSYS environment. The
damages using an ultrasound waves control. The tests realized
technological demonstrator’s geometry, containing the
allow to make an accurate mechanical characterization of the
wireless communication system, is defined during the first
composite materials, analyzing the electromagnetic
preliminary study on the base of the results obtained through
performances of the multi-turn tags and the agreement
fluid-dynamic analysis. Once the demonstrator’s geometry is
between communication systems and composites as well.
defined, it is imported and analyzed within the platform using
the ANSYS code and in particular its ACP module - ANSYS
ELECTROMAGNETIC MODELS
Composite Prep/Post – which represents the most suitable tool
to evaluate the whole composite structure’s performances. The
The IEEE 1902.1 “RuBee” communication standard defines the
ACP’s features allow to manage in an efficient and flexible way
air interface for radiating transceiver radio tags using long
all the pre and post-processing phases, evaluating the
wavelength signals, up to 450 kHz. These devices have a very
industrial feasibility according to the assumed production
low power consumption (a few microwatts), they operate over
process (ACP’s Draping & Flat wrap functions). Moreover, other
medium ranges (0.5 to 30 meters) and at low data transfer
specific features allow to verify damage conditions deriving
speeds (300-9600 bps). To design and optimize the
from in-plane and out-of-plane stress distributions, through
communication systems dipped in a multi-layer composite
Research & Technology Transfer
Newsletter EnginSoft Year 9 n°4 -
43
interface to build the laminate’s stacking sequence for each
design during the optimization process. Through this interface
the definition of the laminate layup is driven by a customized
algorithm that allows to create a symmetric and balanced
laminate, using practical engineering rules based on
sublaminate approach, in order to guarantee an easy
implementation from the production point of view. In this way
the problems caused by technological effects are completely
deleted, avoiding the need to insert any constraint after the
definition of the composite layup within the optimization
process.
Fig. 7 – Sub-laminate approach used by ESAComp-modeFRONTIER interface
for the definition of the laminate’s stacking sequence for each optimization
design
PLATFORM USER INTERFACE
In order to create an accessible and easy-to-use technological
platform and a comprehensible multidisciplinary design
procedure, a Java language user interface is created through a
customization focused on the logical procedure and on the
specific electromagnetic and structural issues studied. When
using the user interface, the designer does not need to edit
the programming code manually; the code allows to manage
automatically the numerical FE models, the input variables,
the objective functions and the file transfers. Through the
interface, the user can edit the ESAComp composite materials
customized multi-failure criteria, such as Max Stress, Max
Strain, Tsai Wu, Tsai Hill, Puck 2D/3D, Hashin 2D/3D, LArC,
Cuntze and so on. During the platform and user interface
development, the debugging of the platform that implements
the design procedure is realized using a simplified geometry in
which the wireless system is contained. Once the main
platform requirements are obtained in terms of effectiveness,
efficiency and flexibility, its
robustness and accuracy are
evaluated analyzing the whole
prototype
structure.
The
technological platform allows
to study the mechanical
behavior of the submarine
vehicle
optimizing
the
performances, according with
the objective functions related
to structural stiffness and
Fig. 9 – Analysis of results obtained through advanced post-processing tools in modeFRONTIER environment
strength.
EFFICIENT LAMINATE DEFINITION PROCEDURE
One of the main results obtained during the development of
the project is the processing and implementation of the
ESAComp-modeFRONTIER interface within the technological
platform. Within the design procedure, ESAComp fulfills the
role of a library, in which the composite material data
collected from the experimental campaign are contained. The
material library is used by the ESAComp-modeFRONTIER
library, some geometrical and functional parameters of the
wireless tag, the technological demonstrator’s geometry and
the loads and constraints operating conditions. The platform
allows to obtain the best solution maximizing or minimizing
the objective functions linked with the structural
performances considering several load cases at the same time.
Fig. 8 – User interface and modeFRONTIER workflow that manage the information and the variables of the
numerical platform’s logical flow
MULTIOBJECTIVE AND
MULTIDISCIPLINARY OPTIMIZATION
Once all the main design parameters are
defined by the interface, the numerical
platform applies the implemented design
procedure working independently. The
information present in the material
library are used to define for each design
the laminate’s stacking sequence with
the rules set in the ESACompmodeFRONTIER interface; the current
composite laminate configuration is
translated and exported for the next
Research & Technology Transfer
44 - Newsletter EnginSoft Year 9 n°4
realized, a final experimental campaign on the whole structure
has been achieved to verify the quality of the electromagnetic
signal within an unfriendly environment.
The dissemination activities have brought a high visibility and
prestige to the partial and final results obtained: the work
progresses have been presented in dedicated sessions at the
“International CAE Conferences” in 2009, 2010 and 2011. At
this year's International Conference, the final results have
been presented during the “Composite Session” where the
presenters showed the technological demonstrator in a
dedicated space within the ESAComp stand.
Fig. 10 – Experimental tests realized on technological demonstrator in
unfriendly environment
steps, represented by ANSYS HFSS (for the electromagnetic
analysis) and ANSYS ACP (for the structural simulations). The
numerical models built are solved and evaluated based on the
strength of the objective functions’ values obtained, then
available modeFRONTIER post-processing features allow to
classify the results with multidimensional diagrams and
charts. For the RuBeeCOMP research project, the postprocessing tools allow to evaluate the electromagnetic
response of the multi-turn printed tag dipped in the fiber-
Fig. 11 – Exhibition of technological demonstrator at International CAE
Conference 2012
reinforced composite laminate and the fiber-reinforced
composite laminate and the structural performances of the
technological demonstrator in several operating load
conditions. In this case the objective functions are
represented by the antenna inductance (L), magnetic field
intensity (H), weight of the structure (W), displacements (D),
Inverse Reserve Factor distribution (IRF). The information
collected through the experimental campaign, preliminary
design analyses and the results obtained through the
platform, allow up to identify the best configuration to realize
the executive design.
CONCLUSIONS AND DISSEMINATION ACTIVITIES
The RuBeeCOMP research project carried out during the last
two years has enhanced the already robust relationship
between EnginSoft, WASS and IDNOVA. The most important
result is the production of the technological demonstrator,
according to the executive design, containing the wireless
communication system integrated within the composite
demonstrator component. Once the demonstrator has been
Research & Technology Transfer
For more information:
Fabio Rossetti, EnginSoft
[email protected]
Meeting conclusivo del progetto
"RuBeeCOMP"
Il Competence Center fiorentino di EnginSoft ha ospitato il
‘meeting’ conclusivo del progetto "RuBeeCOMP" – attività di
ricerca finanziata dalla Regione Toscana nelle modalità del
programma POR CReO 2007-2013.
Obiettivo principale della indagine tecnica è lo sviluppo di
metodologie finalizzate alla progettazione integrata prodotto-processo per la realizzazione di componenti in materiale
composito, caratterizzati da sistemi di comunicazione wireless; quest’ultimi sono concepiti al fine di operare correttamente in ambienti ostili alla radiofrequenza, come ad esempio l’acqua, l’olio, ecc.
Il sistema RuBeeCOMP costituirà elemento principale di eccellenza dell’allestimento tecnologico della piattaforma AUV
(Automonous Underwater Vehicle) denominata V-Fides Progetto di Ricerca al quale partecipa anche EnginSoft – e destinato alla gestione delle comunicazioni da e verso la piattaforma di lancio in acqua e/o a terra. Al sistema è infatti deputato l'onere di ricevere le informazioni dalla base, quindi la
trasmissione alla stessa dei dati raccolti dal drone nel corso
della missione subacquea finalizzata ad operazioni di detezione, esplorazione del fondale marino EnginSoft ha contribuito
al progetto in modo poliedrico; lo sforzo tecnico spazia infatti dalla progettazione e simulazione dell’antenna di trasmissione/ricezione all’ottimizzazione del processo di produzione
del supporto in materiale composito.
All’incontro hanno partecipato tutti i partner che hanno collaborato allo studio e alla realizzazione del progetto:
Whitehead Sistemi Subacquei (Wass), IDNova ed EnginSoft;
inoltre alla riunione erano presente l’ing Vittorio Falcucci, attualmente Direttore tecnico di Eurotorp ma all’inizio dell'attività mentore e fortissimo sostenitore in Wass della liceità e
delle prospettiche aspettative positive del progetto stesso e,
il Professor Giuseppe Martini quale supervisore designato dalla Regione Toscana: tale ruolo, va detto, è stato interpretato
in forma progressiva e stimolante, sicuramente percepibile nel
corso dei meeting per la puntualità e la competenza dei chiarimenti tecnici richiesti.
Newsletter EnginSoft Year 9 n°4 -
45
Le Novità in ambito Mechanical della nuova
Release ANSYS Workbench 14.5
La nuova release 14.5 di ANSYS Workbench, uscita a
Novembre 2012, presenta numerose novità utili nella quotidianità delle applicazioni ingegneristiche.
In particolare, analizzando l’ambiente Mechanical, si possono individuare diverse nuove funzionalità, sia per quanto riguarda la gestione della geometria, la generazione della
mesh, la definizione dei contatti, che per quanto riguarda la
soluzione vera e propria del problema e il post-processamento dei risultati.
Si accenna qui alle più
importanti novità rinviando i lettori interessati al servizio di
assistenza
tecnica
EnginSoft per gli approfondimenti.
Per quanto riguarda la
geometria, è possibile
ottenere
in
DesignModeler, modelli
di più rapida gestione
sia in fase di importazione che in fase di Fig. 1 - Gestione della geometria fino a 10
trasferimento
a volte più rapida
Simulation (velocità
fino a 10 volte superiore per modelli di grandi dimensioni!).
Questo è reso possibile dal fatto che la conversione a
Parasolid non avviene più al momento dell’importazione dell’intero assieme come avveniva nelle release precedenti, ma
solo al momento in cui si definiscano in DesignModeler delle modifiche alla geometria, e solo limitatamente alle zone
interessate da tali modifiche (fig.1)
Riguardo ai contatti, una “matrice dei contatti” configurabile consente una miglior comprensione delle connessioni tra
le parti. Tale matrice è completamente personalizzabile e
consente di gestire sia contatti veri e propri, che connessioni generiche quali spot weld, joint e spring.
E’ possibile inoltre evidenziare i contatti presenti solo su un
singolo corpo o su una named selection, in modo da facilitare la comprensione delle connessioni anche per assiemi complessi (fig.2).
Fig. 2 - Matrice dei contatti
Al fine di facilitare la leggibilità di modelli complessi, sono
disponibili nella nuova release sia filtri basati sul nome dei
componenti o delle named selections, sia la possibilità di utilizzare colori diversi in maniera random per plottare diverse
condizioni di carico, vincolo, diverse named selection così da
renderle facilmente identificabili (fig.3).
Fig. 3 - Colori random per il plottaggio di named selections
Per semplificare l’imposizione di condizioni al contorno o di
carico simili, quasi tutti gli oggetti inseribili in Simulation
possono essere riprodotti e copiati secondo diversi pattern,
mantenendo però inalterati i dettagli dell’oggetto originario.
E’possibile copiare in questo modo, per esempio, l’imposizione del medesimo precarico su un insieme di viti o ripetere gli
Software Update
46 - Newsletter EnginSoft Year 9 n°4
Fig. 4 - pattern di bolt pretension
stessi controlli di mesh su corpi simili (fig.4).
Eseguire sub-model
consente di risparmiare tempo quando si è
interessati a ciò che
accade in dettaglio su
una porzione del modello. Oggi in WB è
completamente implementata la procedura
di sub-model per modelli 3D, in via completamente nativa. La
rimappatura degli spoFig. 5 - Vantaggi derivanti dall’utilizzo della
stamenti nelle zone di tecnologia GPU
taglio non è eseguita
con comandi APDL ma attraverso procedure interne a WB, e
ciò consente di utilizzare le potenzialità di rimappatura già
implementate per l’importazione di carichi ottenuti da solutori esterni (coefficienti convettivi, forze, temperature di
bulk,..).
Per quanto riguarda la fase di soluzione, il metodo “sparse
solver” adesso può utilizzare GPU multiple al fine di ridurre il
tempo di soluzione (fig.5).
Per ridurre le dimensioni dei file dei risultati ottenuti durante il run, inoltre, la memorizzazione di essi viene effettuata
a singola precisione per quanto riguarda le grandezze derivate, come le tensioni e le deformazioni (variabili di elemento).
Per lo stesso motivo, le tensioni principali non vengono salvate nel file dei risultati, ma vengono rivalutate qualora se
ne richieda il plot come quantità di
post-process. In questo modo si riescono ad ottenere file di risultati fino al
50% più piccoli rispetto al passato. Per
modelli con geometria ciclica, al fine
di minimizzare lo spazio di memoria richiesto in fase di plottaggio, i risultati possono essere mostrati ed animati
su una frazione di tutto il corpo simmetrico, scegliendo il numero di settori che si vogliono visualizzare.
Spesso è utile inserire carichi o vincoli
particolari, che possono essere presen-
Software Update
ti in numerose analisi che si vogliono impostare, come opzione dell’ambiente di simulazione. Nuovi carichi e condizioni al
contorno possono essere aggiunti ad ANSYS- Mechanical tramite il nuovo modulo di personalizzazione ACT (per esempio
condizioni al contorno acustiche). E’ possibile inoltre creare
risultati personalizzati, come ad esempio il plot di criteri di
massimo ammissibile basati su un rapporto di tensioni vs una
proprietà del materiale, e inserirli nell’albero come un qualsiasi risultato standard. E’ possibile, sempre grazie ad ACT,
utilizzare WB per lanciare solutori esterni o inserire add-on
esterni nell’interfaccia Mechanical.
E’ spesso necessario indagare, possibilmente in modo semplice, le conseguenze di cricche che compaiono in un componente a causa del processo di manifattura o a causa della fa-
Fig. 6 - effetto della presenza di una cricca in un sub-model
tica, al fine di evitare rotture premature dello stesso. Nella
nuova release 14.5 cricche ellittiche possono essere inserite
in geometrie nominali importate in WB, semplicemente definendo un centro di posizionamento associato ad un sistema
di riferimento e le dimensioni della cricca che si vuole rappresentare. La mesh è quindi gestita automaticamente dal
software senza la necessità di ulteriori azioni da parte dell’utente.
I parametri di cricca (K1 per il modo 1, K2, K3, Stress intensity factor, Mixed mode J-integral, …) possono essere postprocessati e visualizzati lungo il path che segue il fronte della cricca, al fine di agevolare la comprensione dei risultati.
Una cricca può essere introdotta anche all’interno di un submodel per ridurre il tempo computazionale totale e allo stesso tempo incrementare l’ accuratezza locale dei risultati ottenuti (fig.6).
Si ricorda che è sempre possibile trovare informazioni relative
alle novità inserite nella release
14.5 all’interno dell’help sotto la
voce “Release Notes”.
Per maggiori informazioni:
Valentina Peselli - EnginSoft
[email protected]
Newsletter EnginSoft Year 9 n°4 -
47
Simulating Gear Pairs
within SIMPACK
SIMPACK, a Multi-Body Simulation software
tool, enables complete mechatronic systems
which include high fidelity drivetrains to be
accurately simulated. The individual forces
acting between the gear wheel teeth can be
easily visualized with force arrows and plotted.
The SIMPACK Gear Pair element enables full
three dimensional behavior such as dynamically
changing angular and radial misalignments to
be investigated.
HISTORY
Fig. 1 - Bevel gear with crowning
Initially developed for Formula 1 high
performance engines back in 2003 (by Lutz Mauer, an
used for achieving the optimum balance between solver
executive board member of SIMPACK AG), the SIMPACK
speed and accuracy. For example, simple one-dimensional
Gear Pair functionality has since been used in a large
elements may be used for torsional analyses whereas
variety of industrial sectors, e.g. automotive, wind, rail,
gearbox elements (e.g. planetary gear stage) may be used
shipping, aerospace, concrete mills, material handling,
for more detailed analyses when reaction moments on the
etc.
housing are required. For simulations where individual
tooth contact forces are required, the SIMPACK Gear Pair
GENERAL
force element, FE 225, may be used. This element enables
the additional analyses of the meshing forces and
In SIMPACK, a large variety of elements are available for
moments, shaft bending, bearing forces, and a host of
the simulation of torque converters. Depending upon the
task at hand, elements of various level of detail may be
other pertinent analyses (Fig. 2).
Gear Pair FE 225 is an analytical element, and therefore,
extremely fast simulation times can be achieved. Graphical
primitives are defined for the gear wheels which are
subsequently used for the force calculations. This results in
accurate animation of the gear tooth contacts and play.
The Gear Pair FE 225 includes the following:
Gear Types:
• Involute spur
• Helical
• Ring
• Rack and Pinion
• Bevel
Fig. 2 - Gear box with Gear Pair forces and other resultant forces
Input:
• Profile Shift
• Backlash
Software Update
48 - Newsletter EnginSoft Year 9 n°4
All modification types can be input for the right and left
flanks or for both together.
Fig. 3 - Motion of floating sun within a planetary stage (© IMM, TU Dresden)
GEAR PAIR FORCE ELEMENT HIGHLIGHTS
For simulating gear pairs with non-parallel axes, “slicing”
of the gear wheel contact area is necessary. This is
achieved by setting a single parameter (i.e. “Number of
slices”) within the gear pair force element. The handling of
the offset angles for helical gears is now fully automatic.
Slicing is also necessary if flank modification is used.
Shuttling forces, i.e. the axial displacement of the contact
forces, is included. In the case of helical gears, this will
result in an additional tilt moment.
Users can easily switch on and off, and choose between,
various output value types. This enables easier handling
and a more efficient use of data storage space. The
different types of output are described below.
GEAR PAIR DATA CHECK
In order to check the input parameters and initial
conditions of the gear pairs within a model, a user can
perform a “Test Call”. This will result in a list being
generated for each gear pair consisting of important input
parameters and calculated data. Information such as the
theoretical center distance, radial offset, axial offset,
transverse contact ratio, overlap ratio, and total contact
ratio will now be readily available.
Fig. 4 - Bevel gear primitives
• Viscous and Coulombic damping
• Tooth profile and flank modification.
Simulated Behavior:
• Meshing frequencies
• Shuttling forces
• Dynamically changing misalignments
(radial and angular).
GEAR PAIR PRIMITIVES
For all gear pair types, tooth and flank
modification is available.
The modifications are primarily used for
smoothing the non-linear internal
excitations due to the continually
changing number of teeth in contact. The
following modification types have been
added:
• Tip (Fig. 5)
• Root
• Circular
• Left and Right Side
• Lead Crowning (Fig. 6)
• Input Function Array
GEAR PAIR OUTPUT VALUES
By way of parameterization, a user can choose for which
gear pairs the “Basic Output Values” will be generated.
These values include such data as the
relative angles and angular velocities,
“total normal contact stiffness” and
the “dynamic transmission error”.
Similarly, a user can also choose
which “Advanced Output Values” are
to be saved (Fig. 8). These values are
primarily used for analyzing the
coupling forces of the gear pairs,
either for the sum of all teeth in
contact or the individual tooth-pair
contacts. In addition the “Advanced
Fig. 5 - Tip profile modification
Output Values” enable easy animation
of the force arrows in the
PostProcessor (Fig. 9).
After an integration run is complete a
user can subsequently choose which
output values to generate. Re-running
the time integration is not necessary.
Only re-performing “measurements” is
required.
Fig. 6 - Crowning, left and right flank
Software Update
CONCLUSION
The SIMPACK Gear Pair Force Element
is an important component in the
analysis of drivetrains. Full three
Newsletter EnginSoft Year 9 n°4 -
dimensional non-linear dynamic behavior can be
investigated. Customer specific tooth profile and flank
modification enables accurate simulation of meshing
frequency excitations. Easy animation and plotting of
contact forces accelerates comprehension of the dynamic
non-linear behavior. Although major milestones in the
development of the SIMPACK Gear Pair element have
already been achieved, further development will continue
to be implemented, enabling the Gear Pair to fulfill the
even more demanding customer requirements of the future.
For more information:
Fabiano Maggio, EnginSoft
[email protected]
Fig. 7 - Rack and pinion gear
Fig. 8 - User choice for advanced
output values
49
TechNet Alliance Fall Meeting 2012
26th -27th October, Kassel - Germany
The Fall Meeting of the TechNet Alliance, one of the world's
largest networks of engineering solution providers, has taken
place at the Schlosshotel Bad Wilhelmshöhe in Kassel on the
last days of October.
Apart from the many interesting lectures, the leading theme
of the meeting was a full immersion into the HPC environment
for technical computing. To update the audience from around
the world on the latest developments in this area, three
exciting presentations were delivered:
1. Herbert Güttler from MicroConsult provided a detailed
history of HPC and a comparison chart which allowed the
delegates to “travel” through the years, various versions
and hardware of HPC and GPU performances in ANSYS.
2. Dejan Milojicic from Hewlett Packard spoke about his
comparisons of different commercial cloud computing
solutions for true HPC calculations in the engineering
market.
3. Johannes Heydenreich, PhilonNet Engineering Solutions,
presented his company’s experiences in setting up a
remote cluster utilization at the University of Athens.
Mr Güttler’s speech was an extremely deep analysis of multi
GPU performances on single and multi-node clusters. It
covered a very complex benchmark which was impressive in
terms of its good scaling results in the thermo-elastic-plastic
mechanical scenario. Already during the presentation, it
became clear that it would be quite time consuming to carry
on the work.
Key points of the presentation where, among others, the speed
performances of releases 14 and 14.5 on the new Intel
platforms E5-26XX (due to compiler optimized code) and
GPU/CPU scaling in both the PCG and Direct Matrix Solver.
Dejan Milojicic presented a wide spectrum of benchmarks
performed on commercial cloud computing services with
respect to performances of multi-core scientific (chemical and
number crunching) calculations. The findings were, as a
professional user would expect, the following:
- Commercial real HPC cloud computing can only be delivered by a limited number of providers
- All web offers are only able to provide, in most cases, 4
cores and no real high speed interconnection.
- True HPC for scientific computing has to be provided by
specialized companies.
Mr Heydenreich’s brief presentation was about the real use
case of setting up a remote visualization for scientific
computing at the University of Athens. He presented web
components that have been chosen to deliver services to
students and professors on a centralized cluster system for
both calculation and visualization.
Fig. 9 - Animation arrows of normal loads “Indiv. load (fl_n) i,k”
For more information:
Gino Perna, EnginSoft - [email protected]
Software Update
50 - Newsletter EnginSoft Year 9 n°4
ENGINSOFT coordinates the new “MUSIC”
European Project
After a long procedure, the “MUSIC” project
times, and shorter intervals between
(the acronym stands for: “Multi-layer
successive generations of products.
control & cognitive System to drive a metal
Therefore, MUSIC is strongly aimed at
and plastic production line for Injected
leading EU-HPDC/PIM factories, for a
Components”) has finally received the
cost-based competitive advantage
positive approval of a technical and
through the necessary transition to a
scientific Committee. The decision-makers
demand-driven industry with lower waste
are responsible for selecting Collaborative
generation, higher efficiency, robustness
IP Projects in the FoF-ICT sector (Factory of
and minimum energy consumptions. The
Future and Information & Communication Fig. 1 - MUSIC PROJECT LOGO
development and integration of a
Technologies) applied to energy-aware,
completely new ICT platform, based on
agile manufacturing and customization.
an innovative Control and Cognitive system linked to real time
The core concept of the project focuses on the result of the
monitoring, allows an active control of quality, avoiding
analysis and the possible improvements that can be achieved
defects or over cost by directly acting on the process-machine
and applied to the two most representative large-scale
variables optimization or equipment boundary conditions. The
production-lines in the manufacturing field: High Pressure Die
Intelligent Manufacturing Approach (IMA) works at machineCasting (HPDC) of light alloys and Plastic Injection Moulding
mould project level to optimize the production line starting
(PIM). Both are of strategic importance to the EU industry
from the management of manufacturing information. An
which is largely dominated by SMEs.
Intelligent Sensor Network (ISN) monitors the real-time
Due to the high number of process variables involved and the
production acquiring the multi-layers data from different
non-synchronization of the process control units, HPDC and
devices and an extended meta-model correlates the input and
PIM are most “defect-generating”. Moreover, “energy
sensors data with the quality indexes, energy consumption
consumption” processes in the EU industries provide less
cost function. Data homogenization, centralization and
flexibility to any changes in product and process evolution.
synchronization are the key aspects of a control system to
Owing to both of these factors, sustainability requires that
collect information in a structured, modular and flexible
machines/systems are able to efficiently and ecologically
database.
support the production with higher quality, faster delivery
Process simulation, data management and meta-models are
the key factors to generate an innovative Cognitive system to
improve the manufacturing efficiency. The MUSIC project is an
FP7 European project that introduces new ICT technologies at
manufacturing plants with introduces significant potential
impacts: (i) it can strengthen the global position of the
European manufacturing industry; (ii) it can create a larger
European market for advanced technologies such as electronic
devices, control systems, new assistive automation and
robots; (iii) it improves the intelligent management of
manufacturing information for customization and
environmental friendliness.
The MUSIC project’s final target is the transformation of an
extremely conventional manufacturing sector such as HPDC of
light alloys and PIM of polymers into an Intelligent
Manufacturing System, capable of zero-defect production,
Fig. 2 - MUSIC core concept
Research and Technology Transfer
Newsletter EnginSoft Year 9 n°4 -
Fig. 3 - MUSIC project structure in EUCOORD
energy saving and cost reduction. The achievement of this
target passes through multi-level objectives, contributing to a
knowledge-based and dynamic management of HPDC/PIM
manufacturing data.
The MUSIC Project started on September 1st, 2012 and will run
for 4 years, under EnginSoft Coordination and Management,
with more than 9 million Euros of costs, two thirds funded by
the European Commission.
MUSIC is a fully integrated project, since the Consortium is
constituted by 16 complementary European members
(ENGINSOFT SPA, ELECTRONICS GMBH, HOCHSCHULE AALEN,
MAGMA GMBH, UNIVERSITA DEGLI STUDI DI PADOVA – DTG,
FUNDACION TEKNIKER, FUNDACIO PRIVADA ASCAMM, OSKAR
FRECH GMBH CO KG, TOOLCAST SNC, MAIER, S.Coop. AUDI
AKTIENGESELLSCHAFT, RDS MOULDING TECHNOLOGY SPA,
MOTUL SA, REGLOPLAS AG, FRAUNHOFER-GESELLSCHAFT ZUR
FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V, ASSOMET
SERVIZI S.R.L) which cover with their different activities and
know-how, the entire value-chain, from RTD to demonstration,
from prototyping to standardization, as described in the 8
work-packages into which the project is subdivided.
For a more efficient and easy management of the project,
EUCOORD is proving a very useful tool, since it is a web-based
collaborative tool specifically designed for Project
Management and Financial Accounting.
It assists Coordinator and Partners in keeping the project on
track, allowing project structure handling (details on Workpackages, Tasks, Milestones, Deliverables, in terms of technical
content, leadership, duration and deadlines), correct data
collection (partners information, profiles, contacts, detailed
activities assignment with related resources), accounts
management (inputs of costs and effort provided by partners
are stored and validated by the coordinator), reports
generation and disseminations planning, web-site creation,
management and customization, including also a passwordprotected area for internal communication and document
sharing, also of confidential nature. The starting point of the
project was marked in Vicenza, on September 17th and 18th
2012, when the Kick-off Meeting took place. A group of 60
people representing the 16 partners engaged in the project,
gathered at the University of Padova located in Vicenza, for a
two-day meeting. The meeting content was articulated in
three different sessions aiming respectively at:
51
1. Analyzing the state of the art of the control for different
devices in the production line.
2. Providing attendees with general information concerning
management & coordination, communication strategies,
project content and structure, partners’ interactions and
contributions, responsibilities and duties in compliance
with the contract and its annexes.
3. Presenting WP1 tasks and objective so to focus and
structure the first RTD objectives to be discussed and
performed.
The activities performed by now are mainly concentrated in
the technical and scientific tasks of WP1 and management
(WP8) as well.
First project dissemination activities have been promoted so
to give visibility to project existence by presenting the public
summary and objectives in two different international event,
ALUMINUM 2012 (Düsseldorf Messe, 9-11 October 2012) and
INTERNATIONAL CAE Conference (Lazise – Verona, 22-23
October 2012). As soon as first results and achievements will
be available, further actions will be planned for targeted
knowledge transfer and sharing. In this perspective the
project has been submitted to NAFEMS World Congress of next
year (Salzburg – June 2013). The MUSIC Project web site has
been submitted to the European Commission on November
Fig. 4 - The kick-off meeting in Vicenza
15th, 2012. It describes the structure, contents and
functionalities
of
the
Project
portal:
http://music.eucoord.com/ and its connection with the
EUCOORD platform for Project Management.
This first meeting has been very successful, especially because
all of the participants were enthusiastic to start the new
challenge and at the same time could share with each other
their cutting-edge technologies and knowledge. These
exchanges among the partners are fundamental for a positive
beginning of the project. The enthusiastic and promising
assertiveness is essential for good and profitable results to
move from “music” to “symphony” in manufacturing
production lines!
For more information:
Nicola Gramegna, EnginSoft
[email protected]
Research and Technology Transfer
52 - Newsletter EnginSoft Year 9 n°4
Modellazione e Progettazione
Ottimale di Strutture Ceramiche
Un progetto di ricerca e innovazione nell’ambito dei Partenariati e percorsi
professionali industria-università
Il gruppo di ricerca in Meccanica dei Solidi e delle Strutture
del Dipartimento di Ingegneria Meccanica e Strutturale
dell’Università di Trento coordina il progetto INTERCER2, finanziato dalla Comunità europea nell’ambito degli IAPP
(Partenariati e percorsi professionali industria-università). Il
gruppo di ricerca è guidato dai professori Davide Bigoni e
Luca Deseri e include tra i suoi componenti il professor
Massimiliano Gei e i ricercatori Francesco Dal Corso, Andrea
Piccolroaz e Roberta Springhetti.
Il progetto INTERCER2 mira ad un approfondimento della conoscenza scientifica del processo produttivo della ceramica,
con il duplice scopo di ottimizzare la produzione e sviluppare nuove strategie tecnologiche ed industriali che consentano di ridurre i costi di progettazione e fabbricazione dei componenti ceramici, migliorandone contemporaneamente la
prestazione e l’affidabilità. Gli obiettivi verranno raggiunti
sia attraverso la modellazione della compattazione delle polveri e del processo produttivo sia mediante lo sviluppo di
strutture e materiali ceramici multifunzionali avanzati.
L’industria ceramica è un settore ampiamente consolidato in
Europa e le ceramiche avanzate sono cruciali nello sviluppo
di nuove tecnologie, con applicazioni alla nanotecnologia;
tuttavia la produzione industriale delle componenti ceramiche si basa ancora spesso su processi empirici, non sempre
sufficientemente razionalizzati e difficilmente controllabili,
con la conseguente generazione di quantità rilevanti di scarti e residui di produzione.
Il progetto di ricerca è focalizzato sulla modellazione meccanica, implementazione numerica e simulazione dei processi
produttivi, con particolare riguardo alla simulazione dei processi di formatura delle polveri ceramiche, dove il gruppo di
Meccanica dei Solidi e delle Strutture ha già un’esperienza
ben consolidata. Usando tecniche moderne basate sulla teoria dell’elastoplasticità si è infatti sviluppato un modello costitutivo che, tarato su prove meccaniche con protocollo preparato ad hoc, permette la simulazione di processi di formatura a freddo rendendo possibile la determinazione dello
‘spring-back’, delle distribuzioni di densità, stress residui e
delle caratteristiche elastiche interne al pezzo a fine forma-
Fig. 1 - Grafici, da sinistra: distribuzioni di stress residuo, densità di vuoti e modulo di elasticità tangenziale nel componente ceramico a termine del processo
di formatura. I risultati sono ottenuti da simulazioni numeriche in cui è implementato un modello costitutivo specifico per le polveri ceramiche compattate a
freddo sviluppato dal gruppo di Meccanica dei Solidi e delle Strutture dell’Università di Trento.
Research and Technology Transfer
Newsletter EnginSoft Year 9 n°4 -
tura. Attraverso lo strumento su cui il gruppo di ricerca sta
lavorando è possibile ottimizzare la forma dello stampo e la
composizione delle polveri per ridurre lo scarto e ottenere
pezzi di caratteristiche meccaniche ottimali.
Più nel dettaglio, gli argomenti che saranno sviluppati nel
progetto di ricerca sono i seguenti:
Formatura di polveri ceramiche. Si svilupperanno strumenti
per la modellazione e la simulazione del processo di formatura, basandosi su teorie costitutive innovative per la descrizione delle proprietà meccaniche dei materiali ceramici. Tali
modelli saranno fondamentali per l’implementazione in codici numerici e la loro applicazione allo sviluppo di nuove e più
efficienti tecnologie di produzione.
Trattamento di composti ceramici. Una profonda comprensione dell’influenza dei parametri del materiale alla scala micrometrica all’interno del processo permetterà di raggiungere
elevati standard di qualità nella produzione e sinterizzazione
della ceramica.
Miglioramento delle proprietà delle ceramiche. Si affronteranno problematiche legate alla meccanica della frattura ed
alla caratterizzazione delle ceramiche e dei materiali compositi, impiegando in maniera duale l’approccio sperimentale e
tecniche numeriche. In particolare si svilupperà una tecnica
speciale per la simulazione delle proprietà ceramiche capace
di descrivere i complicati processi di nucleazione del danno e
di propagazione della frattura. I risultati numerici verranno
verificati mediante varie tecniche a raggi x in-situ ed in laboratorio ricreando ambienti realistici.
Modellazione di componenti meccaniche in presenza di difetti. Strutture ceramiche con difetti e interfacce imperfette, con enfasi sull’interazione fra incrinature e microstruttura, verranno analizzate mediante modellazione analitica e
numerica.
Nuove applicazioni tecnologiche per i materiali ceramici.
L’obiettivo è la modellazione e progettazione di prodotti ceramici innovativi contenenti strati sottili d’interfaccia ed
aventi proprietà multifunzionali.
Il progetto è inoltre volto a stimolare la mobilità intersettoriale e a migliorare la condivisione delle conoscenze tra i
partner del consorzio, in particolare mediante l’assunzione
di ricercatori esperti, il distaccamento di personale dall’accademia al settore industriale e viceversa e l’organizzazione di conferenze internazionali, workshop e seminari.
Il consorzio responsabile del progetto di ricerca, oltre
all’Università di Trento, vede la partecipazione delle università britanniche di Liverpool e Aberystwyth e di due industrie. I partner industriali sono la EnginSoft, che si occupa
degli aspetti computazionali della modellazione di componenti ceramiche, e la Sacmi, gruppo internazionale e leader
mondiale nel settore delle macchine per la produzione di
ceramici.
53
Davide Bigoni e Luca Deseri
Università di Trento
Gruppo di ricerca in Meccanica dei Solidi e delle Strutture
http://ssmg.unitn.it/
Sito del Progetto INTERCER2
http://intercer2.unitn.it/
EnginSoft ed il progetto
INTERCER2
EnginSoft contribuirà al progetto collaborando con le
Università e con Sacmi per lo sviluppo e l’implementazione di
modelli di simulazione del processo di formatura del materiale ceramico. A partire da modelli esistenti in letteratura, che
faranno da banco di prova, fino ad arrivare all’implementazione delle equazioni costitutive innovative per la descrizione
delle proprietà meccaniche della ceramica che andranno declinate all’interno dello strumento FEM in relazione ai tipi di
analisi richieste. Non solo, EnginSoft potrà contribuire anche
alla caratterizzazione degli stessi materiali sulla base di dati
sperimentali e utilizzando ove necessario tecniche DOE
(Design of Experiment) per la definizione di un preciso piano
di esperimenti siano essi fisici o virtuali atti a comprendere
al meglio la sensibilità dei più significativi parametri di uscita rispetto a quelli di ingresso
Una volta disponibili modelli rappresentativi del fenomeno
sarà possibile anche implementare metodologie utilizzabili al
livello industriale, ed atte alla ottimizzazione del processo di
produzione delle ceramiche o parti di esso, processo che ha
come fine ultimo lo sviluppo di prodotti ceramici innovativi.
Il progetto pur operante sul piano della ricerca e difatto rilasciando indicazioni ingegneristiche di contenuto innovativo
è già noto nelle problematiche ed in metodologia per effetto
di recenti attività svolte dal team di EnginSoft
Il contenuto delle attività di analisi è la realizzazione di una
procedura numerica tale da consentire la determinazione della forma dello stampo di un semplice componente ceramico
per ottenere una precisa geometria della ceramica a valle del
processo produttivo di essicazione e cottura.
Tuttavia lo studio è da intendersi come preliminare, in quanto le leggi che descrivono il comportamento del materiale in
queste due fasi, sono ricavate da modelli semi-empirici noti
in letteratura. Tali leggi potranno essere sostituite da modelli più accurati in eventuali fasi successive di analisi.
In estrema sintesi lo studio si sviluppa sulla capacità di riprodurre una geometria in formato 3d in seguito ad una serie di analisi pilotate autonomamente ed automaticamente
dal software e a partire da una popolazione di forma iniziali
fino ad arrivare alla forma ottima in grado cioè di ridurre al
minimo la differenza tra la forma finale ottenuta numericamente e quella obiettivo desiderio del marketing.
Per ulteriori informazioni:
Francesco Franchini, EnginSoft
[email protected]
Research and Technology Transfer
54 - Newsletter EnginSoft Year 9 n°4
Corsi di Addestramento Software 2013
L'attività di formazione rappresenta da sempre uno dei
principali obiettivi di EnginSoft.
Per ciascuno dei possibili livelli cui la richiesta di
formazione può porsi (quella del progettista, dello
specialista o del responsabile di progettazione), EnginSoft
mette a disposizione la propria esperienza per accelerare i
tempi del completo apprendimento degli strumenti
necessari con una gamma completa di corsi differenziati
sia per livello (di base o specialistico), che per profilo
professionale dei destinatari (progettisti, neofiti od
analisti esperti).
La finalità è sempre di tipo pratico: condurre rapidamente
all'utilizzo corretto del codice, sviluppando nell'utente la
capacità di gestire analisi complesse attraverso l'uso
consapevole del codice di calcolo. Per questo motivo ogni
corso è diviso in sessioni dedicate alla presentazione degli
argomenti teorici alternate a sessioni 'hands on', in cui i
partecipanti sono invitati ad utilizzare attivamente il
codice di calcolo eseguendo applicazioni guidate od
abbozzando, con i suggerimenti del trainer, soluzioni per
i problemi di proprio interesse e discutendone
impostazioni e risultati.
Anche per il 2013 EnginSoft propone una serie completa
di corsi che coprono le necessità di formazione all'uso dei
diversi software commercializzati.
Le novità proposte, confermano che l’idea che EnginSoft
ha della formazione non è una realtà statica che si
ripropone uguale a se stessa di anno in anno, ma è un
divenire, guidato dall'esperienza accumulata negli anni,
dall'evoluzione del software e dalle esigenze delle società
che si affidano a noi per la formazione del proprio
personale. In tale contesto EnginSoft organizza e sviluppa
anche attività didattiche attraverso un programma
formativo personalizzato, soluzioni di progettati in
relazione alle necessità e alle specifiche esigenze
aziendali del committente.
Training
In particolare, l’offerta dei corsi ANSYS viene ridefinita
ogni anno per adeguarsi, sia all’evoluzione del software ed
alle caratteristiche dell’ultima versione disponibile, che
all’introduzione di nuovi moduli e solutori.
In tale senso si segnala:
• in campo fluidodinamico-strutturale l'introduzione,
accanto ai corsi tradizionalmente erogati, del corso
ANSYS CFX - MECHANICAL: Corso Interazione FluidoStruttura.
• in campo fluidodinamico l'introduzione del corso
ANSYS CFD: Corso Avanzato di Aeroacustica.
Sono stati inoltre rivisti ed aggiornati i corsi relativi a
tutti gli altri software sostenuti da EnginSoft per
adeguarli allo stato attuale delle relative distribuzioni.
In particolare per quanto riguarda SCILAB si evidenzia
l’introduzione di un nuovo corso:
• SCILAB-03-IT: Introduzione a Xcos e Modelica.
Dal punto di vista organizzativo nel 2013 tutte le sei sedi
EnginSoft saranno impegnate nella formazione, dando la
possibilità agli utenti di scegliere la location a loro più
conveniente in termini di vicinanza geografica alla propria
società.
Tutto questo a riprova dell'impegno nella formazione che,
per EnginSoft, è e rimane un punto fondamentale della
politica aziendale, un impegno costante verso
l'eccellenza, un servizio per fare crescere i suoi clienti e,
se lo desiderano, crescere con loro.
www.enginsoft.it/formazione
Segreteria organizzativa: [email protected]
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56 - Newsletter EnginSoft Year 9 n°4
International CAE Conference: like never before!
More than 700 people from all over Europe attended the 28th edition of the International CAE Conference. Special
guest Professor Parviz Moin, from Stanford (USA), presented innovation algorithms aimed to simulate large scale
CFDs models.
The edition 2012 of the “International CAE Conference”,
was held October 22nd and 23rd, at the Hotel Parchi del
Garda in Lazise, Verona – Italy. More than 700 people
coming from all over the world and representing the fields
of research, academic and the companies operating in the
sector attend the Italian landmark event in the world of
simulation technology and CAE (Computer Aided
Engineering). Dozens of international companies and
institutions engaged in the event, hardware vendors (HP,
IBM) and CAE solution’s providers: EnginSoft, ANSYS,
EESTECO, Mentor Graphics, Lms , AVL, SCSK and many
others. Special guest, during the morning section, was
Professor Parviz Moin, founder and director of the Centre
for Turbulence Research at Stanford University (California).
An initiative created in 1987 as a research consortium
between NASA and Stanford University and is dedicated to
the study of turbulent motions; it concerns many different
areas of our daily lives: from aviation to wind energy, from
medicine to biology. Professor Moin has pioneered the use
of Large Eddy Simulation, which is a particular
methodology for the simulation of turbulence and a
reference point in the sector.
The conference opened with a letter by Giorgio Squinzi,
President of Italian Industrial Association –
CONFINDUSTRIA - who, despite his absence, wanted to
express his good wishes. Squinzi highlighted the need on
the part of companies "to roll up their sleeves and tackle
contingencies, without losing sight of the competitive
environment in the medium term," stressing that "the
issues addressed in the CAE Conference are
undoubtedly exceptional competitive levers
for the development of better products and
reduced operational costs and times".
Fig. 1 - Prof. Parviz Moin, University of Stanford, special guest of the 2012 CAE Conference
Events
Professor Moin, in his speech, emphasized the
role played by simulation in terms of business
and investment as well as in occupation.
"Simulation is important because it improves
efficiency for companies and decreases costs he explained. Virtual testing today is used not
only to validate laboratory experiments but
mainly to make new discoveries, in addition, of
course, to the work of designing new products.
Simulations are more accurate; in particular
the carrying out of the design phase has
improved 20 thousand times since the origins.
“Where is simulation used? As Moin explains, it
Newsletter EnginSoft Year 9 n°4 -
Fig. 2 - The Plenary Session
is an advanced technology that touches all sectors: from
the design of aircraft turbines to the analysis of pollution,
passing through automotive cooling systems. "Virtual
simulation can become an opportunity for employment for
young people: "Industry is adopting simulation in the
process of design and production, so there are
great opportunities for work - concluded
Professor Moin. But it is essential to focus on
a type of education that has a solid foundation
in calculus, physics, and computer science".
Among the leading companies present at the
event, is EnginSoft, a world leader in
innovation consulting, testing and virtual CAE,
as well as being a sponsor of the conference.
Stefano Odorizzi, President and Founder of
EnginSoft, highlighted, in his speech, that
simulation has grown over the years and he
especially emphasized the large number of
areas where it can be applied."Through
numerical simulation it is possible to
reproduce the behaviour of a particular subject
in a potentially infinite number of diverse
situations. From mechanics to fluid dynamics,
from acoustics to the biomedical sector,
simulation allows great strides forward, as it
accurately reproduces reality. We have learned
that networking is the key to promoting
innovation, because each sector has
something to offer in terms of know-how. By
joining forces we can get better results".
Simulation has positive repercussions in the
biomedical field, as testified by Andrea
Remuzzi, Director of the Department of
Biomedical Engineering at the Institute of
Pharmacological Research Mario Negri.
Remuzzi presented the research project for
"validation of computational models for
surgical planning of vascular access in
57
haemodialysis patients". Currently there are
about 2 million people worldwide suffering from
end-stage renal disease, a condition that in most
cases requires haemodialysis. As explained by
Remuzzi, currently the leading cause of morbidity
and hospitalization in haemodialysis patients
consists of the short and long-term dysfunction
in the vascular access used to connect the
patient's bloodstream to the artificial kidney.
"Through this project - said Eng. Remuzzi –
computational tools have been developed with
the specific aim of preventing complications
during surgery". The next step will be to validate
this study on the clinical front, in order to be able
to understand the effectiveness, functionality and
impact of this new tool that could pave the way
for other simulation applications in the
biomedical field.
For more information:
[email protected]
www.caeconference.com
Fig. 3 - Attendees at the Technical Sessions
Fig. 4 - Attendees at the Exhibition Area
Events
58 - Newsletter EnginSoft Year 9 n°4
CAE Poster Award:
A reward to the genius of young researchers
As part of the CAE Conference, a prize has been awarded to the top six innovative ideas in the field of simulation.
Amongst the winners: The University of Padua, the Mario Negri Institute and the Polytechnic of Milan.
The CAE Poster Award is an award for the genius, the
commitment and the resourcefulness of young people,
researchers and businesses. Among this year's winning
posters are: an innovative motorcycle helmet, a project that
simulates the restructuring of the Arena of Verona, a method
for the treatment of heart disease, new solutions in the
automotive field.
This award demonstrates that simulation can be a real
opportunity for young people, in their exchange of ideas with
companies and institutions, to reach new frontiers in
occupation and employment. The Poster Award is a project
promoted and sponsored by EnginSoft, a world leader in
innovation consulting, with the aim of promoting and
spreading the culture of simulation and of rewarding the
quality of new developments by young researchers. Six of
them have been rewarded for their innovative ideas in the
use of virtual simulation technology.
The competition was divided into two categories: Industry
(for companies) and Academy (for universities) and saw the
participation of more than 50 students and businesses from
all over Italy and Europe. An initial selection of the 10 best
posters in each category was made by a Scientific Committee,
who later announced the three winners for the Industry and
three students for the Academy section, who won a Tablet PC
each.
The event, hosted by Luca Viscardi, of Radio NumerOne, was
attended by Stefano Odorizzi, president and founder of
Events
EnginSoft, and Andrea Remuzzi, Director of the Department
of Biomedical Engineering at the Institute of
Pharmacological Research Mario Negri.
Odorizzi said that he was pleased with the competition: "The
Poster Awards were a success. Many projects were submitted,
much beyond our expectations. Through this undertaking we
wanted to create an opportunity for interaction between the
business world and the universities."
Over 50 projects were presented, 31 of which reached the
final stage. They are mostly posters created by young
students from Italian universities, particularly from those of
Padua, Salento, Basilicata and Ferrara, from the Milan and
Turin Polytechnics, from the Universities of Bologna, Cassino
and Pisa. One of the projects comes from the Mario Negri
Institute, while, amongst the companies, we note Mox-Off,
Pierburg Pump Technology and LyondellBasell.
Eng. Remuzzi, representing the Mario Negri Institute,
stressed the important role that virtual simulation can have
in the biomedical sector, "Biomedicine needs these new
technologies to test new and different techniques, in order
to achieve important results".
As for the students, the winners were:
• Davide Bertini, from the University of Padua; Mr Bertini
submitted a poster on the simulation of renovation of
complex historical buildings, such as the Arena of Verona;
Newsletter EnginSoft Year 9 n°4 -
59
• Matteo Longoni of Mox-off; Mr Longoni implemented a
project to simulate the comfort of a motorcycle helmet
while aiming at reducing time and costs associated with
the design phase;
• Marco Stevanella, from Polytechnic of Milan; Mr
Stevanella presented a study to detect and quantify aortic
malformations, which affect about 2 percent of the
European population.
Amongst the companies and the research community, the
winners were:
• Massimo Nutini, who submitted a poster on the
characterization of plastic reinforced with glass fibre,
widely used in most industrial productions. Nutini works
for LyondellBasell, the third largest independent chemical
company in the world;
• Lorenzo Botti, from the Mario Negri Institute, presented
a study, on an open source software platform, concerning
a system that simulates blood circulation;
• Giorgio Peroni of Pierburg Pump Technology presented a
poster on the vacuum pump, for automotive applications.
For more information:
EnginSoft Marketing Department
[email protected]
EnginSoft sostiene le attività di Ricerca dell'Istituto Mario Negri di Milano
Venerdì 30 Novembre Stefano Odorizzi,
ha visitato la sede di Milano - Bicocca
dell’Istituto Mario Negri per rinnovare la
collaborazione tra EnginSoft e la
Fondazione iniziata in occasione
dell’International CAE Conference 2012.
Silvio Garattini, fondatore e Direttore
dell’istituto di ricerche farmacologiche,
ha accompagnato il CEO di EnginSoft in
una vista ai laboratori e agli strumenti in
dotazione alle centinai di ricercatori che si adoperano quotidianamente nella comprensione degli intimi meccanismi di
funzionamento degli organismi viventi ed individuare le ragioni per cui insorgono le varie malattie in seguito all'introduzione di sostanze estranee.
Nel corso dell’incontro Odorizzi ha consegnato al Professor
Garattini un contributo di destinato ad alimentare le attività
della Fondazione.
“Ringrazio EnginSoft, e la sensibilità dell’ingegner Odorizzi,
per l’attenzione dimostrata al lavoro svolto dell’Istituto – ha
dichiarato Silvio Garattini -. Il sostegno profuso da Aziende e
privati cittadini è un pilastro fondamentale e strategico sul
qual poggia il Mario Negri. Questa generosità consente a tutti noi di combattere, da oltre 50 anni, la quotidiana battaglia
contro le malattie dell’uomo”.
“EnginSoft sostiene da sempre la Ricerca e le iniziative atte a
valorizzare il capitale intellettuale dei giovani ricercatori e
riteniamo questa collaborazione con il Mario Negri un ottimo
modo per farlo – afferma Stefano Odorizzi -. Ringraziamo il
Professor Silvio Garattini per averci
dato questa preziosa opportunità e ci
auguriamo che ci siano altri importanti
progetti per unire le nostre forze”.
L'Istituto di Ricerche Farmacologiche
Mario Negri è un'organizzazione scientifica che opera nel campo della ricerca
biomedica. È stato costituito giuridicamente nel 1961 e ha iniziato le attività
nella sede di Milano il 1° febbraio 1963.
L’impegno della fondazione guidata da Silvio Garattini si articola, oltre che sulla Ricerca Farmacologica, anche
nell’Informazione e Formazione. Infatti l'Istituto svolge anche
attività di insegnamento per la formazione professionale di tecnici di laboratorio e ricercatori laureati e contribuisce, con molteplici iniziative, alla diffusione della cultura scientifica in campo biomedico: sia in senso generale che a specifico sostegno
della pratica sanitaria per un uso più razionale dei farmaci.
Tutti possono contribuire a sostengo delle attività dell’Istituto
Mario Negri. I contributi che Enti e Privati Cittadini offrono
all'Istituto di Ricerche Farmacologiche Mario Negri sotto forma
di liberalità, donazioni e lasciti ereditari sono devoluti a incrementare i programmi di ricerca per lo studio delle più gravi
malattie che affliggono l'uomo e a istituire borse di studio per
i giovani ricercatori cui saranno affidate le ricerche future.
Dettagli sulle attività di Ricerca, e come sostenerle con un contributo tangibile, possono essere consultate sul sito web
dell’Istituto: www.marionegri.it
Events
CAE Poster Award 2012: Winners
Dipartimento di
Costruzioni e Trasporti
Introduction
The simultaneous need to preserve historic heritage and to appreciate its seismic
vulnerability requires the development of techniques and methods used to properly
establish the structural behaviour of historical monuments .
Method
resulting from non-destructive diagnostic tests, carried out on the masonry structures
of the building, which allow to detect the real mechanical behaviour without loss of their
functionality and efficiency.
Steps of the work
The work has required the completion of the following basic steps:
x creation of a Finite Element Model complete in terms of structural geometry, loads,
constraints and material properties;
x recovery of data from experimental studies previously carried out in significant
positions of the monument;
x calibration of the model on the basis of the results of tests in situ.
Assumptions
The starting hypothesis on which is based the development of the entire modeling is
the use of materials with a linear elastic constitutive law .
This assumption is generally recommended especially for qualitative analysis designed
to asses the structural behaviour of a complex building.
Simulation and experimental validation
The Finite Element Model of the whole building was refined and calibrated on the
basis of data from experimental investigations carried out on the so-called "Ala" ,
t
vibration modes, it was obtained a significant correspondence between simulation
what is left of external ring after destructive past earthquakes.
and experimental results which has allowed to judge the correctness of the dynamic
In 1996 were realized some tests to determine its structural behaviour in relation to
behaviour of the Finite Element Model.
dynamic stresses: the acquisition of the signals was made with four accelerometers
placed in pre-selected points of the structure.
The Frequency Response Function obtained represents the deformability of each
point of the structure to vary the excitation frequency.
Modal shapes resulting from dynamic simulation applied to the Finite Element Model
[m]
Mode 01
Mode 02
Mode 03
Frequency 1,68 Hz
Frequency 2,42 Hz
Frequency 4,91 Hz
Mode 04
Mode 05
Mode 06
Frequency 5,89 Hz
Frequency 6,20 Hz
Frequency 7,18 Hz
P03 P01
Experimental Frequency Response Function for control points P01 and P03
P04 P02
1.4E-04
1.2E-04
1.0E-04
8.0E-05
6.0E-05
4.0E-05
2.0E-05
0.0E+00
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
14.0
[Hz]
Findings
The modeling has been conducted assuming a linear elastic behaviour of all materials.
This approximation has proved to be very useful to develop a model sufficiently
accurate, avoiding the complications introduced by the use of non-linear diagrams.
The validity of elastic modeling is demonstrated by the fact that the starting model,
without corrections for adaptation to experimental values, has directly provided results
very close to reality.
Future developments
The study could be further developed taking into consideration the real constitutive
laws of materials and the localized phenomena of deterioration which may affect the
structural behaviour of the building.
CAE Poster Award 2012: Winners
A multiphysic approach
to improve helmets comfort and
reduce time and costs in design process
Longoni Matteo1, Formaggia Luca2, Ferrandi Paolo1
1
Moxoff Srl, Via D’Ovidio 3, 20131 Milano, Italy
2
MOX - Modeling and Scientific Computing
Dipartimento di Matematica “F. Brioschi”, Politecnico di Milano, Italy
Motivation
Goal
Improve helmet comfort in every-day conditions
Key issue: pleasure of driving and safety
Develop a support design tool for engineers
Simulate helmet performances efficiently
Technology
Starting point: very latest research works
Handling of real and complex CAD geometries
Model coupling: aerodynamics 3D, thermofluid 2D and vibroacustics 3D
Multiphase (water/vapour) flows in porous media (comfort tissue/human hair)
Human head sweating model for heat generation
Advanced numerical methods
Improvement and development of robust simulation codes
Mathematical model
Vibroacoustic model - WIP!
ThermoFluid dynamic problem
Navier–Stokes coupled with Darcy–Forchheimer: Penalized NS
ρCF
μ
(ρ(u · ∇)u − μΔu) χΩf + ∇p +
u + √ |u|u χΩp = 0
k
k
∂T
+ Cf u · ∇T = ∇ · (λp ∇T ) − le s(h, w , T )
Temperature T :
∂t
∂h
Humidity h:
+ u · ∇h = Dh Δh + s(h, T , w )
∂t
∂w
Sweat content w :
= ∇ · (Dw ∇w ) − s(h, T , w )
∂t
Mv
Evaporation rate s: s(h, T , w ) = E
(psat (T ) − pv (h, T )) χw +
2πRT
Ωf ,p ,w = fluid , porous, wet domain
ρ = air density
u = flow velocity
t = time
μ = dynamic viscosity
p = pressure
k = permeability
Dh = water diffusivity
χ = indicator function
Cf , λp , le = thermodynamics
Mv , R, psat , pv = psychrometrics
CF , Dw , E = coefficients
Elastodynamics equations:
⎧
ρ∂tt u − ∇ · σ(u) = f, in Ω × [0, T ]
⎪
⎪
⎪
⎪
on ΓD × [0, T ]
⎪ u = 0,
⎪
⎨
σ(u) · n = t,
on ΓN × [0, T ]
on ΓNR × [0, T ]
⎪ non-reflecting b.c.,
⎪
⎪
⎪
in Ω × {0}
⎪ ∂ t u = u1 ,
⎪
⎩
in Ω × {0}
u = u0 ,
u = displacement
t = time
n = unit normal
σ = stress tensor
u0,1 = initial conditions
f = external force
Ω = 3D domain
Γ = boundaries
Discontinuous Galerkin formulation
Space–Time formulation
Multi-domain formulation
3D hexa mesh
Multiphysic approach
Results
Accurate and efficient simulations of the physics involved
Evaluation tool for engineers to explore different design solutions
Time and costs of the overall design process drastically improved
Optimized process satisfying comfort requirements for a
successful product.
References
P.F.Antonietti et al., “Non-conforming high order approximations of the elastodynamics equation”, CMAME, 2012.
C.Canuto and F.Cimolin, “A sweating model for the internal ventilation of a motorcycle helmet”, Computers & Fluids, 2011.
M.Longoni, L.Formaggia, P.Ferrandi Moxoff, MOX
09/2012
A multiphysic approach to improve helmets comfort
CAE Poster Award 2012: Winners
ZZZELRPHFKSROLPLLW
Healthy and BAV-affected aortic root dynamics:
Fluid-Structure Interaction simulations
from MRI-based 3D models
M. Stevanella1, F. Sturla1,2, C.A. Conti1, E. Votta1, A. Della Corte3, A. Redaelli1
1 Department of Bioengineering, Politecnico di Milano, Milan, Italy
Division of Cardiovascular Surgery, Università degli Studi di Verona, Verona, Italy
Department of Cardiothoracic and Respiratory Sciences, Seconda Università di Napoli, Naples, Italy
2
3
Results and Discussion
Introduction
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CAE Conference 2012
CAE Poster Award 2012: Winners
D i
Design
& CAE
C
Group
G
Europe
e
CAE Support to the Design
n of Parts made of GF
GF-PP
PP*
PP
((*Glass Fiber- Reinfo
orced Polypropylene)
yp py
)
M.Nutini
M
Nutini1, M.Vitali
M Vitali1, M.C.Ferrari
M C Ferrari1, C.Garc
C Garc
cia2, D.Sinnone
D Sinnone1, F.Secchiero
F Secchiero1, F.Weber
F Weber3
1 Basell
Poliolefine italia srl; 2 Basell Poliolefinas Co.
Co Española
a S L; 2 Basell Polyolefine Gmbh; Companies of LyondellBasell
a,S.L;
Abstract
Simplified method based on orthotropic material laws
Glass fiber
Gl
fib reinforced
i f
d polypropylene
l
l
(GF PP) materials
(GF-PP)
t i l are replacing
l i
metal
t l and
d engineering
i
i
polymers
l
i automotive
in
t
ti
structural
t t l
applications Like all glass fiber reinforced thermoplastics,
applications.
thermoplastics GF-PP
GF PP products can show anisotropy caused by fiber orientation induced
by the injection process.
process Taking into account fiber orientation in the simulations allows the designers to improve the accuracy of the
analyses
y
and can avoid some arbitraryy choices needed when using
g an isotropic
p material law.
Two methods are here presented:
A first approach is based on micromechanical modeling through homogenization methods available from commercial software
(Di i t®) This
(Digimat®).
Thi allows
ll
coupling
li
off the
th structural
t t l analysis
l i with
ith the
th fiber
fib orientation,
i t ti
which
hi h is
i obtained
bt i d from
f
th numerical
the
i l
simulation of the injection process.
process
The authors developed a simplified approach where the presence of the reinforcing glass fibers is kept into account using an
orthotropic
p material law. Here the reference directions are g
given byy the material flow direction, which can be obtained from a
moldfilling analysis.
Both the approaches request very simple tensile tests for the determination of the model parameters.
I the
In
th design
d i phase,
h
th choice
the
h i off either
ith approach
h will
ill depend
d
d on the
th problem
bl
t be
to
b studied,
t di d on the
th resources and
d timing
ti i available,
il bl
and on the desired accuracy.
accuracy
A simplified method based on an orthotropic non-linear material law with an already existing Ls-dyna (MAT_103) has been
d
developed.
l
d F
Fundamental
d
t l items
it
off thi
this approach
h are:
Selection of an anisotropic material law ((LS-DYNA
(LS DYNA MAT
MAT_103)
103))
The selected law (Ls-dyna
(Ls dyna MAT_103)
MAT 103) is isotropic elastic - anisotropic viscoelastic; its parameters are identified through the
simulation of the tensile test on two different orientations using
g MOGA ((Multi-Objective-Genetic-Algorithm)
j
g
) based optimization.
p
By so doing, a Pareto diagram is built onto which the best set of parameters is identified.
As for the approach based on micromechanics, using specimens cut from injection molded plaques is of paramount importance to
h
have
th desired
the
d i d orientation
i t ti with
ith respectt to
t the
th flflow and
d similar
i il to
t the
th one obtained
bt i d in
i the
th reall parts.
t
Moldfilling analysis results
(flow directions) transferred
into the structural mesh
Material Structure
IIn a multi-phase
lti h
material
t i l such
h as SGF-PP,
SGF PP th
the mechanical
h i l properties
ti depend
d
d on the
th constitutive
tit ti properties
ti off the
th base
b
materials
t i l and
d
the composite morphology,
morphology ii.e.,
e the weight fraction
fraction, length,
length diameter and orientation of the fibers
fibers. These properties are induced by
material processing,
processing as in the case of injection molding
molding. Here
Here, a classical skin-core
skin core structure is observed and
and, depending on the
thickness,, can be more or less pronounced.
p
Along
g the material thickness,, a central p
portion,, or “core”,, is characterized byy fiber
orientations perpendicular to the flow, and a lateral portion is characterized by fiber orientations parallel to the flow.
Moldflow predicted flow direction as material orientation
Flow direction from a simple filling analysis is transferred to FEA model as material orientation to be used as reference
system for an orthotropic material law.
Failure
criteria
• A critical step which is common to both the approaches is the definition of appropriate failure criteria.
Best results are achieved when failure criteria are implemented with the characteristics as:
A i l tstepi which
Anisotropic
(Orientation
(O
ti dependent)
d to dboth
A- critical
h hi ist common
b ht) approaches
h is the
h d
definition
f
off appropriate failure
f l
criteria.
Strain
dependent
Best
resultsrate
are achieved
when failure criteria are implemented with characteristics such as:
Sensitive to(Orientation
differentiation
tension/ compression
-- Anisotropic
dependent)
Strain rate dependent
Sensitive to differentiation tension/ compression
CT image
g of GF-PP
sample
Source: test performed
for LyondellBasell by
Fraunhofer ITWM
Validation
Several benchmark tests were carried out to validate both the approaches proposed
proposed.
Method based on Micromechanical Modeling
g
Two-scale models are used with a macro-scale associated to the part
p and a micro-scale associated to the material microstructure.
The transition between the two scales can be accomplished through a homogenization process. In this case, fiber content, geometry
and fiber distribution, together with the matrix properties, are the required parameters.
• A first drop test on an injection molded GF-PP box was used to compare the computed force vs. displacement with the
experimental curve. The anisotropic simulation using the simplified method was compared with the isotropic analyses, showing a
d fi it l b
definitely
better
tt accuracy ((shown
h
b
below).
l )
Fundamental items of this approach are then:
Prediction
P
di ti off Fib
Fiber orientation,
i t ti , transferred
t
f
d to
t the
th structural
t
t
l
mesh
Dedicated software as Digimat®
Digimat®-MAP
MAP by e
e-Xstream
Xstream are used to map the fiber orientation,
orientation predicted by moldfilling analysis onto a
p
TRI mesh,, into a shell – QUAD mesh (Fig.
( g a below))
Mid-plane
The fiber orientation is predicted using a transport equation for the orientation tensor components aij . Appropriate parameters – as
th fib
the
fiber interaction
i t
ti coefficient
ffi i t Ci - mustt b
be determined.
d t
i d Thi
This is
i a critical
iti l point:
i t a validation
lid ti phase
h
is
i mandatory
d t
for
f reliable
li bl
predictions Here a comparison with measurement from X-ray
predictions.
X ray tomography is shown (Fig.
(Fig b,
b below)
Da
ij
Dt
2
C I
SRF
1
Z
2
J G
ik
ij
a
kj
a
(3 )a
ij
ik
Z
kj
O §
¨ J ik a
2 ¨©
kj
a
ª
ik
J kj 2 « a ijkl
¬
1
§
¨1 SRF
©
·
¸ L ijkl
¹
M
ijmn
a
mnkl
º»
¼
·
J k ¸¸
• A second
d drop
d
test
t t on th
the same box
b but
b t with
ith an impactor
i
t off larger
l
dimensions
di
i
was used
d to
t compare the
th fracture
f t
patterns.
tt
Th
The
results using the simplified method
results,
method, show a good agreement with the experimental pattern under a great variety of testing
conditions and materials.
materials Shown below is an example reported with a GF
GF-PP
PP having a soft matrix
matrix.
¹
• An impact test on an industrial part as a ribbed beam is proposed for a deeper investigation of the rupture pattern using a
different failure criteria. The results, using a Tsai-Wu model coupled with Ls-dyna MAT_103, show a very accurate reproduction of
the failure pattern.
Fig. a: Orientation tensor mapped from the
TRI mesh used in moldfilling analysis to the
QUAD mesh used in structural calculations
Fig. b: Comparison between orientation
tensor values predicted and measured on a
GF-PP
GF
PP sample
Fig. c: Comparison between
Fig
measured and simulated
tensile stress-strain curves
on specimens cut from a
plaque along different
orientations
Material laws based on Homogenization method
Mean field homogenization software – like Digimat® – are used to predict the non linear constitutive behavior of a multi-phase
material,
t i l combining
bi i the
th characteristics
h
t i ti off each
h single
i l phase
h
iinto
t an h
homogenized
i d law
l
for
f the
th composite.
it
Parameter identification
f
through optimization
Reverse Engineering
g
g is used byy simulating
g the tensile test on specimens
pec
cut from injection
ject
molded p
plaques
aques along
g to different
orientations with respect to the flow to identify the material law parameters (Fig. c above).
Courtesy from Faurecia Seatings
Conclusions
Co c us o s
• Anisotropic materials as GF-PP can be properly modeled using an orthotropic material law, as Ls-Dyna MAT_103, or more
e complex approaches as those based on micromechaiical modeling.
• In both cases,
cases the information from the injection process is critical for the accuracy of the solution and needs to be carefullyy evaluated and transferred to the structural analysis
analysis.
• The
Th results
lt are d
definitely
fi it l more accurate
t th
than simply
i l using
i iisotropic
t i methods.
th d
References
[1] M.Nutini, M.Vitali, “Simulating anisotropy with Ls-dyna in glass-reinforced, polypropylene-based components”, Ls-dyna Anwenderforum
m, Bamberg 2010
[2] C.Ferrari,
CF
i C.Garcia,
C G i M.Nutini,
M N ti i “A
“Assessmentt off Fib
Fiber Orientation
O i t ti
i Injection-Molded
in
I j ti M ld d SGF-PP
SGF PP items“,
it
“ C
Connect!
t! Moldflow
M ldfl
U
Users
Meetin
M ti g 2011,
2011 Frankfurt,
F kf t 2012
[3] M.Nutini,
M Nutini M.Vitali,
M Vitali “Simulating
Simulating failure with Ls
Ls-dyna
dyna in glass
glass-reinforced
reinforced, polypropylene-based
polypropylene based components”
components , Ls
Ls-dyna
dyna German Users Forum,
um Ulm
Ulm, 2012
CAE Poster Award 2012: Winners
An Open-Source Incompressible Navier-Stokes Solver for
Hemodynamic Simulations at High Reynolds Numbers
1,2Lorenzo
2Mario
Botti, 2Bogdan Ene-Iordache,
1,2Andrea
Remuzzi, 2Luca Antiga
1University of Bergamo, Dalmine (BG), Italy
Negri Institute, Department of Biomedical Engineering, Ranica (BG), Italy
INTRODUCTION
RESULTS
Hemodynamic simulations rely on the ability to numerically solve the
incompressible Navier-Stokes (INS) equations in realistic geometries.
Physiological conditions are often associated to moderate or high Reynolds
numbers flow conditions where inertial forces dominate viscous forces.
Convection-dominated incompressible flows constitute a challenging class of
problems both in terms of numerical stability and computational cost.
Re 400
Re 600
METHODS
An INS solver implementation suitable for large scale hemodynamic
simulations in complex three 3D geometries has been recently proposed in
[1]. The discrete formulation is based on a pressure-correction scheme
combining a discontinuous Galerkin (dG) approximation for the velocity and
a standard continuous Galerkin (cG) approximation for the pressure.
•The main interest of pressure-correction algorithms is the reduced
computational cost compared to monolithic strategies.
•The dG discretization of the decoupled momentum equation renders this
method suitable for high Reynolds numbers simulations.
•The cG discretization limits the computational cost associated to the
Laplacian operator in the projection step.
•The space couple is LBB stable for dG(k)-cG(k-1) velocity-pressure pairs
as well as for dG(k)-cG(k) equal order discretizations.
We propose an open-source hemodynamics solver based on this
formulation [Gnuid, http://github.com/lorbot/Gnuid].
•The solver relies on libMesh [http://libmesh.sourceforge.net/] for mesh
management, finite element function spaces and numerical integration.
•PETSc [http://www.mcs.anl.gov/petsc/] ensures efficiency of the solution
process on parallel architectures.
Steady state hemodynamic simulations in an anastomosis surgically created in the arm of an
hemodialysis patient. Bottom, 253.000 elements tetrahedral mesh obtained with vmtk [www.vmtk.org].
Top row, streamlines and velocity volume rendering at Re=400 and 600. dG(2)-cG(1) discretization.
Text
Steady state hemodynamic simulations in a three-bends carotid siphon recontructed from 3D
rotational angiography. Left, computational domain and hybrid mesh obtained with vmtk
[www.vmtk.org]. Right, velocity contours at Re=300, 600 and 1000. dG(3)-cG(2) discretization.
10
Spatial convergence of the finite element discretization evaluated on the steady
counterpart of the Navier-Stokes problem proposed in [2]. We are able to confirm the
theoretical convergence rates regarding to the mesh size h.
11
12
Pulsatile simulation on a three-bends carotid siphon,
Re=400, 1000 time steps per cardiac cycle.
Left, maximum inflow velocity computed by means of the
inverse Womersley method [5], and considering a
physiological trend over the cardiac cycle.
Top row, velocity contours over transversal and
longitudinal sections of the siphon. 77050 elements
hybrid mesh, dg(2)-cG(1) discretization.
CONCLUSIONS
The ability to solve the incompressible Navier-Stokes equations by means of
high order accurate finite element methods has been demonstrated. The fully
implicit discontinuous Galerkin discretization of the advection-diffusion step
extends the applicability of the pressure-correction algorithm to convectiondominated pulsatile flows. The decoupling of the incompressibility constraint
from the momentum equation ensures an effective an robust solution process
based on standard preconditioned iterative solvers.
REFERENCES
1. L. Botti, D.A. Di Pietro, J Comp Phys, submitted, preprint at http://hal.archives-ouvertes.fr/hal00458293/en.
2. C.R. Ethier, D. Steinman, Int J Num Meth Fluids, 19 (1994), 369-375.
3. S. Albensoeder, H.C. Kuhlmann, J Comp Phys, 206 (2005) 536-558.
4. S. Tsangaris, N. Stergiopulos, J Biomech, 21 (1998) 263-266.
Spatial accuracy evaluated on the 3D lid-driven cavity flow at Re=1000.
Top row and bottom row right, streamlines. Bottom row left, comparison with accurate
results presented in [3]. 50x50x50 hexahedral mesh, dG(2)-cG(1) discretization.
The ARCH project is funded by the European Commission within the 7th framework programme
(FP7-ICT-2007-2) grant agreement nr. 224390
http://www.vph-arch.eu
CAE Poster Award 2012: Winners
237,0,=$7,212)$
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66 - Newsletter EnginSoft Year 9 n°4
Le reti d’impresa? Serve un cambio di mentalità
Il convegno di Veneto Innovazione con enti e aziende sul tema delle reti e delle soluzioni per finanziare l’aggregazione
d’impresa. Occorre un cambio di mentalità per andare nel mercato con maggiori opportunità.
Nell’epoca della crisi e della sempre maggiore
competitività, la sfida della cooperazione è una della
prospettive più importanti per le PMI Italiane. Tuttavia,
fare rete vuol dire prima di tutto cambiare la mentalità
degli imprenditori che devono superare lo schema classico
della competizione per ritrovare, nel mercato, dei partner e
non degli avversari con cui condividere un percorso
comune di crescita e di sviluppo. È questo quanto emerge
dal convegno “B2gether”, svoltosi il 22 ottobre 2012,
all'Hotel Parchi del Garda, a Lazise (VR), dal titolo,
“Imprese e competitività, insieme per il successo”.
La tavola rotonda è stata organizzata da Veneto
Innovazione, con la collaborazione del Parco Scientifico
Tecnologico Kilometro Rosso, il consorzio Intellimech,
Fig. 1 - Mirano Sancin, Kilometrorosso, moderatore della Tavola Rotonda
Events
EnginSoft, Habitec (Distretto Tecnologico Trentino per
l'energia e per l'ambiente), Distretto Aerospaziale Pugliese,
Mesap (Meccatronica e sistemi avanzati di produzione) ed
Ecipa, società di formazione professionale.
Mirano Sancin, direttore del Parco Scientifico Tecnologico
Kilometro Rosso ha aperto la conferenza parlando
dell’attuale situazione italiana: “Dobbiamo guardare alla
crisi come a un opportunità – ha dichiarato – perché in
tempi come questi le imprese sono più disponibili a cercare
nuove strade per aumentare i margini di
profitto e quindi più propense verso
l’innovazione”.
Sancin ha proseguito parlando di “Open
innovation” e di quanto la contaminazione di
settori e mondi diversi sia necessaria per
ripartire portando l’esperienza di Kilometro
Rosso.
Ma fare rete d’impresa non è però semplice.
“Sembra quasi che le PMI italiane non vogliano
crescere”. A dirlo è il professor Marco
Vedovato, Direttore del Master in Innovazione
Strategica, Università Cà Foscari di Venezia
intervenuto per conto di Ecipa. “Le alleanze
strategiche sono quelle che sul breve periodo
danno maggiori risultati ma allo stesso tempo
sono associate all’idea di un più alto tasso di
Newsletter EnginSoft Year 9 n°4 -
67
triplicati”. Zangola è tornato poi sulla
necessità “che al vertice ci sia uno staff di
persone in grado di guidare il gruppo verso
l’innovazione”.
Fig. 2 - Partecipanti alla Tavola Rotonda
fallimento”. La motivazione è legata all’innata volontà di
autonomia delle piccole e medie imprese del nostro Paese,
superabile solo attraverso un nuovo approccio più
dirigenziale. “In Italia c’è la volontà di unirsi e di fare rete.
Bisogna saper cogliere le sinergie che ma anche applicare
delle tecniche a livello di management per fare in modo
che le reti funzionino” conclude Vedovato.
Questo tema è stato ripreso anche da Gianni Lazzari,
Amministratore Delegato Habitech, Distretto Tecnologico
Trentino per l'Energia e per l'Ambiente che nel corso del
suo intervento ha dichiarato: “Bisogna puntare alla
complementarietà ma evitando la conflittualità”. Lazzari
ha proseguito parlando dell’aggregazione nel settore edile
e degli strumenti per realizzarla. “L’edilizia stava vivendo
una fase di stallo, era sempre più necessario rinnovare il
settore. Per questo abbiamo creato le filiere”.
La conferenza si è conclusa con gli interventi
di Giuseppe Acierno e Matteo Ametis. Il primo
ha presentato l’esperienza del Distretto
Aerospaziale Pugliese di cui è Presidente e
Amministratore spiegando la necessità
percepita al momento della sua fondazione di
“prendere di petto l’innovazione creando un
distretto che aggregasse e promuovesse le
aziende del territorio”. Ametis, Vice Direttore
di Veneto Innovazione ha parlato invece del
ruolo della Pubblica Amministrazione
sottolineando il fatto che “non deve solo
erogare fondi ma aiutare le aziende a mettere
le basi su cui costruire le relazioni” ma anche
che è necessario cambiare i modelli mentali del
management “vero ostacolo al concetto di aggregazione”.
La tavola rotonda moderata dal giornalista del Sole 24 Ore,
Federico Pedrocchi, è stata visibile anche in streaming web
sperimentando nuove formule di divulgazione dei
contenuti per l’impresa.
Per maggiori informazioni:
Mosè Necchio, EnginSoft
[email protected]
Mauro Zangola, Responsabile di Programma Mesap ha
parlato dell’aumento delle aziende che vogliono entrare
nelle reti d’impresa, facendo specifico riferimento
all’esperienza piemontese. “Le aziende che vogliono
puntare sull’aggregazione sono aumentate gradualmente
nel corso degli anni, non solo nel settore della
meccatronica. Oggi in Piemonte i poli scientifici sono
Events
68 - Newsletter EnginSoft Year 9 n°4
CAE Conference 2012 welcomed Sponsors
from Japan. Post-conference interviews
based on the strong relationships between EnginSoft and its
customers. Mr.Imai: The attendance was high and the conference
place was excellent. We could see that both, the host and the
delegates, were very positive and had high motivations. The
program was well organized and included a variety of topics. We
enjoyed attending different sessions and presentations on
diverse and critical topics.
At this year’s International CAE Conference two Japanese sponsors
participated to introduce their self-developed software products
which are quite unique. Akiko Kondoh, EnginSoft Consultant in
Japan, had the pleasure to meet and interview the representatives
of SCSK Corporation and Cybernet Systems Co.Ltd. after the event.
Interview with SCSK
Akiko Kondoh: What are your main impressions of the
CAE Conference 2012?
Mr.Nakayama: We participated in the conference for the first
time with the aim to investigate the European market for our
products. I can say that we are simply impressed by the strong
presence of EnginSoft in the CAE market which was clearly
reflected by the large number of attendees from the EU and
other, various countries. Although we were worrying about the
turnout before the conference, as we had heard a lot of negative
news about the economic situation in Europe, in Lazise we soon
noticed that our concern proved unfounded. The quality of the
conference was very high, all of the sessions including keynote
speeches, user meetings, and product updates were conducted
extremely well. I think that the success of the conference is
Events
AK: Did you have the opportunity to speak with EnginSoft?
Mr.Nakayama: We appreciated the opportunity to meet with Mr.
Stefano Odorizzi and other members of the EnginSoft team, to
exchange opinions regarding our product. EnginSoft understands
the features and advantages of the product very well. We could
hear positive opinions about the effective use, from the
perspective of the license sales and the consulting and
engineering services for the customers. I believe that EnginSoft
is a real expert organization for engineering and simulation.
Mr.Imai: I feel that EnginSoft has an extensive network and
strong influence on a number of different fields. Another
interesting point we experienced was that EnginSoft provides
CAE solutions from a much wider point of view than CAE
companies in Japan. It appears to us that many of the
challenges CAE engineers are facing in their work are the same
or nearly the same in Italy and in Japan.
An example of a large scale mesh model (20million DOF). ADVENTURECluster
Newsletter EnginSoft Year 9 n°4 -
AK: Apart from the Conference, did you have time to
explore Italy a bit?
Mr.Nakayama: I went to the city of Verona by train after the
conference. The old town, the scenery, the stone pavements and
the river flowing through are just like I had imagined it always.
I enjoyed the atmosphere in the historic city. Unfortunately, I
didn’t have enough time to visit the House of Juliet which is
famous, also in Japan. I hope to visit Verona and Italy again
some time soon and to be able to also stay for a few days as
part of a holiday. Mr. Imai: There was no time for sightseeing
and to visit other places. But I enjoyed the ambience around the
conference venue which was surrounded by vineyards and which
allowed me to enjoy Italy.
AK: Would you say that your presence at the Conference,
also as an exhibitor, was effective?
Mr.Nakayama: The exchange of opinions with EnginSoft and the
opportunity to present our product and case stories was very
valuable for us. On the other hand, it was a pity that we couldn’t
talk enough with the end users directly at the exhibition booth,
to understand the real feedback on our product. I guess one of
the reasons was that this was the first participation in the
EnginSoft Conference and our company name and our product
are not yet familiar to the attendees. We think we should
continue the promotional activities with patience and take time
to explore and position ourselves in the European market.
Lastly, I am really grateful to Ms. Luisa Cunico and Ms. Akiko
Kondoh, for their deep consideration and to everybody at
EnginSoft. Mr.Imai: We could understand the positive attitude
towards CAE and the trend now in Europe. Both was helpful for
us for defining our vision and the directions for our overseas
development. Although it was not easy to obtain in-depth
reactions from the attendees, due to our company being lowprofile in Europe at this time, overall it was absolutely effective
for us to participate in the conference.
69
glad to be able to experience the excellent atmosphere. We
could exchange opinions and information very easily, with
customers and other sponsors and exhibitors.
AK: Did you have the opportunity to speak with EnginSoft ?
Mr.Futura: I was very impressed by the EnginSoft business style.
EnginSoft clearly is not just a software vendor. The company
provides CAE tools to their customers, effective and substantial
technologies, that are complemented with EnginSoft’s
sophisticated engineering services. At Cybernet, we want to do
our best to continue the good partnership with such a great
company.
AK: Apart from the Conference, did you have time to
explore Italy a bit?
Mr.Furuta: I’ve had some time to visit Milano the day before the
conference. Milano’s landmark, the Duomo is a breathtaking
beauty, especially due to its magnificent and sensitive design, I
think. This was my second visit to Italy, and I love it. The
streets and the atmosphere in Italy are always elegant and
beautiful, one can feel the country’s deep culture and rich
history.
Interview with Cybernet Systems
AK: What are your impressions of the CAE Conference 2012?
Mr.Furuta: It was a vigorous conference with so many customers
from different fields, such as ANSYS users, ANSYS
complementary software users, and other CAE engineers, not
only from Italy but also from a wider area in Europe. I was so
PlanetsX: The Injection Molding CAE System fully embedded in ANSYS
Workbench
AK: Would you say that your presence at the Conference,
also as an exhibitor, was effective?
Mr.Futura: Yes, it was very effective for us. Many prospects and
customers visited our booth and attended our presentation. It
was a great pleasure and success for us to meet a new customer
who already said at the conference that he wants to use our
product. We could find an opportunity for PlanetsX to go into
the European market. I hope to participate in the conference
again in the years ahead, to introduce promising CAE topics
from Japan.
This interview was conducted by Akiko Kondoh,
Consultant for EnginSoft in Japan
Events
70 - Newsletter EnginSoft Year 9 n°4
Trainer europei di ANSYS alla scuola EnginSoft
A valle dei costanti e continui confronti tra i rispettivi gruppi
Si è svolto il 13 e 14 Novembre scorso, presso il Competence
di sviluppatori e tecnici, per ANSYS Inc. è del tutto naturale
Center EnginSoft di Firenze, il Corso di Formazione sulle
chiedere a EnginSoft, in quanto profondo conoscitore della
Dinamica Avanzata al quale hanno partecipato i formatori
materia, di organizzare un corso avanzato sulle tematiche di
ANSYS dei principali paesi europei e alcuni Channel Partner.
Dinamica. La didattica di questo appuntamento si è articolata
Pierre Thieffry - Product line manager di ANSYS Inc. per le
su quattro filoni fondamentali:
soluzioni di Meccanica Strutturale - ha affidato ad EnginSoft
• la corretta lettura della fisica che governa il fenomeno
l’organizzazione del corso riconoscendo di fatto al Channel
dinamico da rappresentare;
Partner italiano un ruolo fondamentale nello sviluppo
• la capacità di leggere i dati sperimentali nei formati
tecnologico dei propri prodotti e nel contempo delle risorse
interpretati correttamente dal software;
umane che li devono promuovere e calare nelle differenti
• la metodologia numerica da impiegare per cogliere con
realtà industriali.
attendibilità il fenomeno dinamico in essere;
La particolarità del Corso, ideato strutturalmente da Roberto
• la lettura critica dei risultati, analitici e sperimentali, al
Gonella – executive manager della business unit di EnginSoft
per il FEM - e operativamente coordinato e condotto da
fine di coglierne vantaggi e svantaggi.
Al termine della due giorni fiorentina gli ‘scolari’ coinvolti
Valentina Peselli - specialista tecnica sulle tematiche di
non hanno risparmiato apprezzamenti positivi sia sulla
dinamica avanzata - è da leggersi nella genesi dello stesso.
qualità delle lezioni che il bagaglio di conoscenza espresso
EnginSoft e ANSYS, infatti, interpretano all’interno del
dai tutor che si sono succeduti.
Mercato ruoli diversi ma complementari. ANSYS ha l’onere di
sviluppare nuove capacità di calcolo, e di rappresentazione
A cura della redazione
della simulazione, attraverso le tecnologia agli Elementi
Finiti. EnginSoft è da decenni costante applicatore delle
tecnologie di simulazione e calcolo numerico quindi
rivisita quotidianamente le potenzialità numeriche alla
luce di casi industriali e concreti a contatto diretto con
il Mercato.
Per ANSYS, quindi, l’importanza strategica di un Channel
Partner con le caratteristiche e l’autorevolezza di
EnginSoft è duplice: infatti, da un lato essa consiste nel
riportare, attraverso iniziative quali i “Council Meeting”
e l’analisi tecnica delle richieste di supporto applicativo
ovvero i ‘desiderata’ di ingegneri ed analisti CAE italiani
utenti delle soluzioni sviluppate dall’azienda di
Pittsburgh.
Non meno importante il know-how espresso da EnginSoft
Luxmoore e Alex Pett di ANSYS UK; Sylvain Coste e Simon Mendy di ANSYS
nella conoscenza del valore dei parametri teorici che Joe
Francia; Podbevsek Frans di Infinite Simulation Systems (distributore ANSYS per
compongono l’uso avanzato della tecnologia al fine di l’Olanda); Czyz Tomasz di Mesco (distributore ANSYS per la Polonia); Roberto Gonella
ottenere soluzioni ben rappresentative della realtà di EnginSoft; Davide Fugazza di ANSYS Belgio; Valentina Peselli di EnginSoft; Mauro
Peselli, Advance Dynamic Technical Opinion Leader
simulata.
Events
Newsletter EnginSoft Year 9 n°4 -
Event Calendar
March 20-22, 2013
Ravenna - Italy
Offshore Mediterranean Conference & Exhibition
www.omc.it/2013
October, 2013
Northern Italy
International CAE Conference 2013
www.caeconference.com
CAE CONFERENCE 2012
PROCEEDINGS
June 9-12, 2013
Salzburg - Austria
NAFFEMS World Congress
www.nafems.org/congress/
The Proceedings of the International CAE Conference
are now ready for download on:
http://proceedings2012.caeconference.com
June 19-21, 2013
Mannheim - Germany
ANSYS Conference & 31. CADFEM Users’ Meeting
www.usersmeeting.com
FREE Newsletter
Printed Copy
2013 SEMINARS
Stay tuned on www.enginsoft.it/eventi
for the complete program of seminars in 2013
Do you want to receive a free
printed copy of the EnginSoft
Newsletter?
Just scan the QRcode or connect to:
www.enginsoft.it/nl
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