Case Study - MSC Software Corporation

Transcription

MSCAlpha_Summer05_V5Cover_r12.qxd
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The Journal of Virtual Product Development
Volume 5 | Spring/Summer 2005
Simulating Small Devices,
Reaping Big Rewards
Casio Optimizes Semiconductor Wafer Level
Package Design with VPD
Raising the Roof (Literally)
with VPD-Enhanced Process
Integrated Tools, Nonlinear Analysis
Help ASC Streamline Development
Fueling the Search for
Alternative Energy Sources
Solid Oxide Fuel Cell Development
Gets Hot with VPD
Dr. Moe Khaleel, Pacific Northwest National Laboratory
5/19/05
11:01 AM
Page 2
P16
The
Journal
of
Virtual Product Development
[ On the Front Line ]
Simulation Fuels Advanced Energy Research
[ 16 ]
An Interview with Dr. Moe Khaleel, Pacific Northwest National Laboratory
[ From the Beginning ]
Change: A Necessary Element
[1]
[ Company & Industry News ]
MSC.MasterKey Continues to Win Acceptance
[2]
MSC.Software Builds Sales Channels, Offerings
Learn with Online Webinars
[ Case Studies ]
P8
αlpha
Cover photo of Dr. Moe Khaleel
by Jeff Rickey.
Product News in Brief
P4
“This enhanced MSC.Marc
package...gives us viable
designs very quickly.”
Editor
Carrie G. Bachman
World Editors
Hiroko Fujita
Evelyn Gebhardt
Design
Hae-Jo Shin
Reader comments and
suggestions are always welcome.
P10
Contact the Alpha editorial staff at:
P14
Corporate
MSC.Software Corporation
2 MacArthur Place
Santa Ana, California 92707
Telephone +1 714 540 8900
Europe, Middle East, Africa
ASC Moves to ‘Design, Analyze and Confirm’ Process
with Integrated VPD Tools
[4]
Stephen Doncov
Casio Improves Digital Products
with Innovative Ideas and VPD Technology
Telephone +49 89 431 98 70
[8]
Asia-Pacific
Eriko Asakura; Reiko Ishizuka
CAE Data Management at Audi AG
[ 10 ]
Dr. K. Gruber, Dr. U. Widmann, J. Reicheneder, and J. Eberfeld
Sidebar: Future MSC.SimManager Releases
Invernizzi Presse Gains Safety and Reliability with VPD Tools
MSC.Software GmbH
Am Moosfeld 13
81829 Munich, Germany
MSC.Software Japan LTD
Shinjuku First West 8F
23-7 Nishi Shinjuku
1-Chome, Shinjuku-Ku
Tokyo, Japan 160-0023
Telephone +81 3 6911 1200
[ 14 ]
ZZ*2005APR*Z*ALPHA*Z*LT-MAG
Evelyn Gebhardt
[ Technical Matters ]
The Principles of Nonlinear Analysis
[ 20 ]
Sidebar: LEGO Builds Quality and Safety Using VPD
The MSC.Software corporate logo, SimOffice, MSC, and Simulating Reality, and the names of the MSC.Software products and services referenced herein are trademarks or registered trademarks
of the MSC.Software Corporation in the United States and/or other countries. NASTRAN is a registered trademark of NASA. All other trademarks belong to their respective owners.
© 2005 MSC.Software Corporation. All rights reserved.
MSCAlpha_Summer05_V5_r13.qxd
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[ From the Beginning ]
Change:
A Necessary Element
In today’s business environment, everyone spends an extraordinary
amount of time trying to successfully manage change. ‘Faster, better,
cheaper’ is the race that every company is running. And most of the
time, the company that best manages change and gets ‘category killer’
products to market the fastest and the cheapest usually establishes itself
as the market leader.
Change is a very appropriate topic for my first Alpha magazine column
as MSC.Software’s new chairman and CEO. As many of you know,
MSC.Software’s former chairman and CEO, Frank Perna, retired in
February after seven outstanding years of service to the company.
Everyone in the industry owes him a debt of gratitude, for it was his
vision of the promise of Virtual Product Development (VPD)
that set us on the path we travel today.
The realization of that vision is the reason I chose to join
MSC.Software. Until 2001,
I served as chairman and CEO
of Structural Dynamics
Research Corp. (SDRC) prior
to its acquisition by EDS and
subsequent merger with
Unigraphics. The product lifecycle management (PLM – a concept we
helped develop at SDRC) and VPD worlds are very familiar to me,
and I continue to be amazed at the opportunities for success that
companies in these areas bring to manufacturers around the world.
Indeed, Daratech, an industry analyst firm that closely follows these
markets, is forecasting that CAE/VPD currently accounts for about
25% of all PLM spending and will grow more than 10% in 2005.
Bill Weyand
Chairman and CEO, MSC.Software
than Virtual Product Development solutions to accelerate time-tomarket. After all, the most important questions to any manufacturer
– will the product work the way the customer expects it to, and can
we increase our profits and revenue? – are best answered by VPD.
Combining virtual product development technologies and traditional
physical testing methods can ensure optimal product performance
while at the same time reducing development time and costs.
So, while the name on one of our office doors has changed,
MSC.Software’s strategy remains the same – to be a trusted advisor
to our customers around the world by helping them improve their
processes and products through Virtual Product Development. What
will change? We’ll make some changes to our infrastructure to improve
the ways that we do things, but we’re confident that these changes will
not only make us a better company, but will make it easier for you to
interact with us and get the
most out of your product
development investments and
resources.
“Those who best manage change are
in the best position for success.”
This growth is occurring for one simple reason: VPD is the
best way to effectively understand and manage change related to
product performance. By better understanding and managing product
performance, manufacturers can improve time-to-market and grab
market share.
Before I made the final decision to join MSC.Software, I did a good
deal of research about the company, including reading the many
return-on-investment (ROI) success stories that you, our customers,
have worked with us on over the past years (you can review them at
success.mscsoftware.com).
Those who best manage
change are in the best
position for success. If there is one constant in the world economy and
especially in the manufacturing markets, it is that the speed of play is
ever-increasing. The demands on manufacturers continue to become
more severe – better products manufactured in less time, with fewer
resources, with more regulatory and safety requirements, and a
continual focus on the bottom line.
MSC.Software stands ready to help our customers meet these
challenges head-on. I will be traveling extensively in the first half of
2005, meeting with my new team members at MSC.Software and
with customers around the world. I look forward to discussing these
and other issues with you further. Once again, I am excited about the
opportunities for our joint success in 2005 and beyond. While some
things may change, rest assured that our partnership with you and our
commitment to helping you succeed remains constant. α
These success stories made me extremely enthusiastic about
MSC.Software’s business and our leadership position in the market.
I can think of no better investment for a manufacturing organization
[1]
5/25/05
2:58 PM
Page 2
[ Company News ]
Learn with Online Webinars
Product News
in Brief
MSC.MasterKey Continues to
Win Acceptance
Fiat Group (Turin, Italy) has renewed its
worldwide corporate agreement with
MSC.Software. Under the three-year contract,
Fiat companies (including FIAT Auto, Alfa
Romeo, Ferrari, Maserati, Centro Ricerche
Fiat, COMAU, IVECO, Case New Holland,
Irisbus, ELASIS, and Magneti Marelli) will
extend and promote the use of MSC.Software
products in all of their product line
engineering centers.
www.fiatgroup.com
The Friedrich-Alexander University of
Erlangen-Nuremberg and Regional
Computing Center (RRZE), its IT
service provider, have signed the first
MSC.MasterKey license agreement by a
university customer in Europe. The agreement
includes access to MSC.Software’s SimOffice
products MSC.ADAMS, MSC.Nastran,
MSC.Patran, and MSC.Marc. Students in
different university departments, including
engineering, material science, engineering
mechanics, quality management, engineering
design, production engineering, and systems
engineering can now take advantage of the
breadth and depth of MSC.Software tools for
research and science within a single, crosscampus licensing system.
“MSC.MasterKey really meets our needs,”
said Dipl.-Ing. Hans Cramer, RRZE director.
“We appreciate this broad range of solutions
at a convenient pricing scheme for universities, as well as the consultation we are
receiving from MSC.Software. We expect our
students’ research to benefit greatly from the
new possibilities.”
Fincantieri is one of the largest, most
diversified shipbuilding concerns in the world,
with more than 9,200 employees and design
centers in Genoa and Trieste. The company
builds vessels at eight shipyards, and is
recognized for its leadership in passenger ships
and large, high-performance cruise ferries. α
SimDesigner 2005 r2 for CATIA
V5R14 has been released. SimDesigner for CATIA V5 is a suite of embedded simulation
tools that allow CATIA users to streamline and automate the task of building and testing
virtual prototypes by simulating motion, stress, fatigue, heat transfer, and other physical
performance attributes. The product family currently includes Generative products, which
embed simulation capabilities directly into the CATIA V5 CAD environment, and
Gateway products, which provide smooth, direct access to Virtual Product Development
tools such as MSC.Nastran, MSC.ADAMS, and LS-DYNA.
www.fincantieri.com
SimDesigner 2005 r2 has a number of new features, including:
www.cetena.it
• SimDesigner Suspension (SDS) – Flexible parts are now incorporated into suspension
design, allowing design engineers to get more realistic results.
• SimDesigner Motion (SMO) – Load transfer to SimDesigner Linear (SDL) allows users
to investigate component stresses resulting from operating motion.
• SimDesigner Fatigue (SFA) – Integration with SimDesigner Flex (SDF) enhances
durability prediction by including transient stress time histories of flexible components.
www.rrze.uni-erlangen.de
Fincantieri Group’s Naval Vessel Business
Unit and the Group’s R&D company,
CETENA, have implemented the MSC.MasterKey
license system at their product development
site in Genoa, Italy. A long-time MSC.Software
customer, Fincantieri wanted to streamline its
development process and needed flexible,
optimized access to VPD tools.
• SimDesigner Linear and Advanced Structures Professional (SDL and ASP) – Extends
support for beam simulation to account for bending stresses, axial stresses, and forces on
standard beam sections.
• SimDesigner Composites (SCP) – Leverages the CATIA Composites Design (CPD)
definition to predict composite structural performance, helping manufacturers reduce
the time needed to design composites parts.
simdesigner.mscsoftware.com
MSC.Nastran now supports 64-bit Intel® Xeon processors, extending its long-standing
support of the 64-bit Intel® Itanium® 2 platform. Xeon processor-based workstations
feature large cache sizes and Intel Hyper-Threading Technology tailored for multi-tasking
environments. MSC.Nastran is optimized on the Intel platform to promote exceptional
performance, reliability, and lower total cost of ownership. The MSC.Nastran release also
includes advanced optimizations for Itanium 2-based platforms.
MSC.Software Builds Sales Channels,
Offerings through New Partnerships
MSC.Software and INCAT have announced
a partnership in which INCAT will market
and sell SimDesigner 2005 r2 for CATIA V5
to North American manufacturers, with
MSC.Software providing training and
support services.
“We want to improve our indirect channel
and ensure that we have the broadest coverage
possible, especially within the small- and
medium-sized manufacturing market,” said
Raymond Gaynor, vice president,
Business Development and Customer
Support, MSC.Software. “We look forward
to working with INCAT to meet customer
demand for robust and easy-to-use CADembedded tools.”
In an expansion of its current partnership
with Dassault Systèmes, MSC.Software will
now distribute and implement DELMIA
Digital Manufacturing Solutions in the
Americas under an agreement with Delmia
Corp., a Dassault Systèmes company.
DELMIA products offer manufacturers the
technology and the collaborative environment
to digitally define the way products are
manufactured. Offerings range from process
planning to general assembly processes and
factory simulation across all manufacturing
segments.
BOM: Bill of Materials
DMU: Digital Mock-Up
MPM: Manufacturing Process
Management
CAM: Computer-Aided
Manufacturing
PDM: Product Data Management
CAE: Computer-Aided
Engineering
CAD: Computer-Aided Design
MSC.Software also recently announced the availability of MSC.Nastran for 32- and
64-bit AMD Opteron™ processor-based systems. The 64-bit version of MSC.Nastran
on AMD Opteron processor-based systems has demonstrated performance improvements
of up to 15% compared to similar engineering simulations run on a 32-bit architecture.
www.mscnastran.com
MSC.SuperForge and MSC.SuperForm 2005 have been released. Providing integrated
2D and 3D finite element analysis for numerous component-manufacturing applications,
the bundled products help engineers evaluate and optimize forming and forging processes
with virtual computer models rather than performing costly trial-and-error tests on the
shop floor. MSC.SuperForm 2005 has been enhanced with better automatic remeshing
technology, damage prediction, multistage analysis, and capabilities for simulating more
forming processes such as blanking, glass forming, and hydroforming.
Robert Barlow, vice president, Channel
Development, Delmia Corp., said, “The
inclusion of DELMIA solutions in both
the Dassault Systèmes PLM offering and
MSC.Software’s VPD product line gives
MSC.Software the opportunity to provide
its customers a comprehensive, end-to-end
solution for the optimization of product
design and manufacturing processes.” α
Both products are easier to use and provide a robust solution to manufacturing challenges.
Additional new features include:
• Integration of solver technologies allows forging and forming simulations to be
evaluated from one integrated set of tools via customized, discipline-specific interfaces.
www.delmia.com
In the Winter 2005 issue of Alpha, several ‘slices’
of the PLM Marketplace chart on page 12 were
mislabeled. The corrected chart is shown here.
We apologize for the error.
MSC.Software
Visit webinars.mscsoftware.com for the
schedule of live events, and follow the
simple registration process. If you can’t
join in a live presentation, the sessions
are archived so you can access them
whenever your schedule permits.
Here’s a short sampling of archived
sessions now available:
Customer Spotlights
• Boeing’s Use of System Simulation
for Space Flight Program
• Radian’s Rapid Development
of Stronger Armor for U.S.
Military Vehicles
On-Demand Product Series
• SimDesigner 2005 r2 for CATIA V5R14
• What’s New: MSC.Nastran 2005;
MSC.ADAMS 2005; MSC.Patran 2005;
MSC.Dytran 2005; MSC.Marc 2005
• 2005 SimOffice Product Release
On-Demand VPD Solution Series
• VPD for Biomechanics Applications
• Simulating Durability and Fatigue
• System-Level Simulation
with MSC.EASY5
• Improving the Product Development
Process with the VPD Maturity Model
• Improved materials properties such as enhanced elastic and plastic materials data.
• New functionality for press simulation of spring-supported dies, multiple-object
dies, and hammer and screw press multiblow simulations.
• Stochastic Simulation using
MSC.Robust Design
• Improved post-processing capabilities, including real-time cutting views and
rotational cutting. α
superforge.mscsoftware.com
[2]
Through our free, online Webinars, you can
learn what’s new in the latest releases of
MSC.Software products; get an in-depth
look into the use of Virtual Product
Development (VPD) applications in a
variety of industries and disciplines; and
discover how other companies are
innovating with the help of VPD. Presented
by subject experts from MSC.Software, our
partners, and our customers, the sessions
are interactive, with live discussions and
the opportunity to ask questions.
• Managing Simulation Process
and Engineering Data with
MSC.SimManager
• Enhanced process tree visualization, meshing, and input data options.
www.incat.com
Keeping up with advances in simulation
technologies, computing resources,
software releases, and new application
methods can be challenging. Since it’s
not always possible to take time away from
the office, MSC.Software delivers the
information to your desktop.
/
superform.mscsoftware.com
[3]
5/25/05
2:58 PM
Page 4
[ Case Study ] ASC
[ Case Study ] ASC
Areas of high stress and failure found with
SimDesigner Nonlinear analysis closely matched
those identified during physical testing. The
redesign determined no areas would fail, which also
correlated with physical testing.
A convertible top header latch, which secures
the front bow of a convertible top to the
windshield frame structure, is a complex
mechanism with as many as 10 or 20 parts
made of different materials that deform
plastically differently. These types of latches
are challenging for CAE software because of
the many design issues and tradeoffs to be
considered, such as contacts, joints, flexible
bodies, and multiple material properties.
The ASC design engineering team had been
making do with linear analysis, which could
show where issues existed but was unable to
address the high nonlinear stress ranges ASC’s
products experience. Additionally, ASC was
looking to streamline its product development processes with integrated tools to
minimize the time and cost of designing
and testing latches.
ASC Moves to
The ASC design engineering team
determined that an integrated CAD-CAE
environment provided by embedded CAE
tools was best suited to help solve complex
linear, nonlinear, and dynamic problems.
In turn, these virtual product development
(VPD) tools allow validation of operational
effort, load capacity, and abuse testing. The
VPD tools are part of ASC’s strategy for
migrating to Design-Analyze-Confirm
processes and away from Design-Build-TestBreak processes.
The design engineering team’s task was to
ensure that the top header latch mechanism
functioned within customer-supplied
requirements for operational effort, abuse,
and load capacity. Although the design was
built in CATIA V4, CATIA V5 FEA/DMU
Kinematics and MSC.Software’s SimDesigner
Motion and SimDesigner Nonlinear tools
were utilized. During an earlier evaluation,
the V5 analysis tools were found to be
robust, quick, and easy to use because
the V5 generative design approach utilizes
feature recognition. When features on a part
are changed, it is automatically remeshed.
Using V5 models and a generative approach,
the productivity gain more than made up
for the time lost converting the V4 models.
For this header latch, it was particularly
important to identify areas of
nonconformance and provide feedback that
could be used to make engineering changes.
The results were validated in SimDesigner
‘Design-Analyze-Confirm’ Process
with Integrated Simulation Tools
Few would argue the powerful attraction of a sunny day, an
Eclipse Spyder, and numerous appearance programs and
open road, and a convertible-top vehicle – it’s a common
body packages for such products as the Dodge SRT-4,
visual cue for freedom. One company known around the
Dodge Viper SRT-10, and Pontiac Grand Am SC/T.
world for its commitment to the advancement of open-air
The company’s passion for innovation is obvious from its list
engineering is ASC International.
of ‘firsts’: the first modern retractable hardtop, the first
Founded in 1965 as American Sunroof Company and
factory-installed power sunroof in North America, the first
headquartered in Southgate, Mich., ASC helps automakers
inwardly folding convertible top, the first glass panel sunroof,
design, engineer, and manufacture high-impact, low-volume
and the first modular sunroof. Its latest advance, the patent-
specialty vehicle programs. The company’s award-winning
pending xpanse™ Convertible-Top System, was unveiled in
programs include the first retractable hardtop on a truck
January 2005 on the ASC Helios, the world’s first modern
chassis, the 2003 Chevrolet SSR, which won a 2003 Chrysler
four-door convertible.
Group Gold Award and a Gold Award in the 2004 Industrial
In the following case study, Stephen Doncov provides
Design Excellence Awards. ASC has also developed
in-depth insight into the evolving role of Virtual Product
convertible systems for the Toyota Solara and Mitsubishi
Development in ASC’s design process.
Stephen Doncov is a CAE specialist with ASC Incorporated
in Southgate, Michigan.
[4]
MSC.Software
Nonlinear with physical testing from a
previous latch design. The analysis closely
matched the areas of high stress and failure
identified with physical testing. Furthermore,
analysis of the redesign indicated no failures,
which also correlated with physical tests.
Another factor for consideration was
that the production method for many of
the parts is different than the one used for
making a physical prototype. For example,
prototype die-cast zinc parts are made using
investment casting. Consequently, a different
material could be used in the prototype.
Typically, the properties of the material in a
physical prototype are lower, which makes the
final determination of the production part
properties more difficult. The confidence
in an analytical model representing a
production unit or assembly is much higher
because the properties of the die-cast
(production) material are used. Without
analysis, the possibility existed for overengineering the part.
For this latch, customer requirements
included operating range, abuse (vertical
and side force), and maximum load. A
motion simulation was used to determine
if the effort required to open and close the
latch met the 40 to 60N requirement. Three
nonlinear analyses were run to determine the
effects of abuse, including a 600N opening
force on latch handle, a side load of 294N,
and a maximum load of 4900N applied to
the hook. This last requirement was to ensure
the mechanism wouldn’t break under some
extraordinary and unforeseen event.
Motion Analysis Study
The force required to close the latch mechanism was found to exceed the specified range.
Latch handle abuse analysis in SimDesigner Nonlinear on the modified design
indicated the handle satisfied the vertical abuse specification.
Operational Effort
The model of the header latch mechanism
was created using CATIA’s DMU Kinematics
tool to move the handle to the fully opened
position. The handle was constrained to
ground, which actuates the model. Torsional
springs were inserted between the hook clamp
body and roll pin 1, and between the lock
button and the long roll pin. The leaf springs
were approximated using linear springs and
dampers for the handle detent spring and the
handle-to-idler spring.
The latch mechanism is quite complex and
involves a lot of contact and features that
cannot be modeled kinematically. Kinematics
approximates the operation of the latch but
doesn’t consider the physics. The motion
analysis in SimDesigner Motion considers the
physics. For example, it determines if the
springs are too strong or too weak and
provides force deflection curves. Kinematics
or animation software can’t do that.
[5]
5/25/05
2:58 PM
Page 6
[ Case Study ] ASC
“...Virtual product development (VPD) tools
allow validation of operational effort, load
capacity, and abuse testing.”
The stroke of the latch was simulated with a
prismatic joint, allowing the receiver
to travel along the stroke direction of the
latch. The approximate load of the top cover
was modeled by utilizing a linear spring along
the travel path. As the receiver is pulled, the
load increases from zero to a maximum value.
Because SimDesigner Motion considers the
physics of the model, it allows interaction
between bodies. For this analysis, 3D contacts
were utilized. All of the contacts were
modeled, including the hook-to-roll pin,
handle stop to detent spring, lock button to
mounting bracket, lock button to handle,
idler to handle in two places, handle to lock
button, and hook to receiver. The leaf springs
were approximated, using linear springdampers with a revolute (hinge) joint where
the pivot would be.
The motion study confirmed the proper
operation of the latching system, including
the interaction of latch handle and idler
bracket. The latch capture range (latch stroke)
was verified along with the operation of the
handle lock. However, SimDesigner Motion
identified spikes of 77N and 88N in the
effort required to move the handle, exceeding
the requirement of 40 to 60N. Looking at the
mechanism as it engaged clearly showed the
dowel pin bottoming out before the handle
locked. This caused the spike in force. By
using a finer hook adjustment, the handle
locked before the dowel pin bottomed out
in its receiver.
Nonlinear Analysis
Abuse – Vertical Force
The abuse analysis was used to determine
if the handle would break when an opening
(vertical) force of 600N was applied. If the
handle bent, it was not considered a failure.
A linear analysis was run to determine which
parts could be omitted to save nonlinear
analysis computing time. Parts not reaching
their yield strength and not critical for
maintaining the integrity of the mechanism,
such as connecting pins, were eliminated,
reducing processing time.
Initially, all the parts were meshed with
Tetrahedron 4 elements (tet4’s), which are
linear brick elements. They are very stiff
elements that reduce compute time. Since
the nonlinear analysis determined all the
[6]
MSC.Software
high-stress area hot spots were located in
the handle, all the parts were kept as tet4’s.
The handle was set to tet10, a higherorder element.
Using the local mesh feature, a finer mesh
was used in the critical stress areas. Local
sag conditions were implemented around
the area of contact and hot spots. The ability
to use localized refined meshing provides
higher accuracy results in the critical areas
identified during the linear analysis and
substantially reduces processing time.
SimDesigner Nonlinear allows different types
of contact between bodies to be defined. For
example, when looking for tangency, contact,
or an impact, it allows two bodies to be
constrained as always glued together,
intermittent contact, or never touch.
This allows the user to decide how the
individual parts will interact, which makes
the solver more efficient and further reduces
processing time.
The clamp mounting bracket and both
handle-to-idler hinge pins were constrained.
For bodies that do not collide and bodies
contacting themselves, contact was set to
inactive, eliminating their consideration. The
bodies that did not need to rotate in relation
to one another were set to glue. The bodies
that could come in and out of contact with
one another or would need to rotate relative
to one another were set to touch. A 600N
load was applied in the vertical direction
of the face near the end of the handle.
For the material properties, ZA-8 zinc,
the same material used in production parts,
was used for all the components, except the
connector pins, which were 1010 steel.
ASC and MSC.Software provided the
nonlinear material properties. Although
the curves were not validated with
physical testing, this can be an important
consideration. Any cold-working or heat
treatment of the parts can lower or raise
the yield and ultimate strength, dramatically
affecting the nonlinear material curve.
The contact bias was set at 90%, allowing
the solver to converge faster because it doesn’t
have to drive down to an exact solution.
Contact bias is a numerical method to help
convergence in contact analysis using
MSC.Marc, the solver used by SimDesigner
[ Case Study ] ASC
Nonlinear. For some applications, the contact
bias helps improve stability in contact
analysis. Coulomb friction was activated
because friction affects material deformation
or material flow on the contact boundary.
This in turn is reflected in force and stress,
etc. Additionally, friction generates heat,
which affects material properties in thermalcoupled analysis.
As mentioned earlier, the physical prototype
was made of ZA-12, which is not as strong
as the production material ZA-8. VPD tools
enabled the use of ZA-8 production material
properties, which with satisfactory correlation
would provide data for determining the
performance of production parts.
The handle design was simulated using
ZA-12 and ZA-8 material properties.
Additionally, a physical prototype was made
with ZA-12 and tested to validate the results.
The vertical abuse test of the initial design
indicated the ultimate stress was exceeded in
the handle using ZA-8 at approximately 60%
of the load. The actual results were:
Test
Material
Fail Load*
Physical Test
ZA-12 (317MPa)
270N
Simulation
ZA-12 (317MPa)
230N
Simulation
ZA-8 (374MPa)
370N
Original Design Tests
*Approximate
The handle design was modified and another
simulation performed using ZA-12 and ZA-8
material properties. Another physical
prototype was made with ZA-12 and tested
for correlation. The actual results were:
Test
Material
Fail Load*
Physical Test
ZA-12 (317MPa)
780N
Simulation
ZA-12 (317MPa)
600N
Simulation
ZA-8 (374MPa)
1250N
Redesign Tests
*Approximate
The redesign using ZA-8 material
properties provided an approximately 200%
safety margin, which satisfied the vertical
abuse specification. Additionally, a simulation
was run using the ZA-12 material properties,
which indicated a failure at 600N. The
physical test using the ZA-12 material
determined that failure would not occur
until 130% of the load was achieved
(approximately 780N). This was within
25% of the simulation results, which was
within ASC’s correlation target.
CATIA’s DMU Kinematics tool was used to move the model to the fully opened position.
SimDesigner Motion was used to build the model’s motion constraints, including handle
to ground, and to insert the torsional springs by hooking the clamp body to roll pin
1 and the lock button to the long roll pin.
Because SimDesigner Motion considers the physics of the model, it allows interaction
between bodies. For this analysis, 3D contacts were utilized. All of the contacts were
modeled. The leaf springs were approximated, using linear spring-dampers with a
revolute (hinge) joint where the pivot would be.
Abuse – Side Load
Normally, a failure happens when somebody
applies too much force on the handle.
Therefore it was important to know what
would happen if the handle was left half open
and got caught on somebody’s shirt, or what
would happen if somebody tried to muscle
open the latch with too much force. Would
the handle bend or break off?
The same boundary conditions, constraints,
material properties, meshing, and solver
settings were used for the 294N side load
analysis as in the vertical load analysis. The
original design satisfied the side load abuse
design requirement.
Alternate Failure - Maximum
Load Analysis
The alternate failure analysis was a customerrequired test to make sure the hook could
withstand a high-impact event. In this case,
the hook had to withstand a maximum load
of 4900N in the latch stroke direction.
As in previous simulations, linear analysis
was used to determine which parts could
be omitted from the nonlinear analysis.
In this case, all the parts were eliminated
except for the clamp body, hook, roll pin
1, and receiver.
All of the parts were meshed with tet4
elements and, as earlier, a nonlinear analysis
was run to identify the hot spots for high
stress. The first simulation was used to refine
the mesh. The receiver and roll pin remained
tet4 elements. However, the clamp body and
hook were re-meshed with tet10 elements.
The local meshing and sag conditions were
implemented around the contact areas
and hot spots.
An advanced restraint was applied to roll pin
1, allowing only translational displacement in
the latch stroke direction. The two translation
New Process, New Advantages
degrees of freedom (DOF) in the non-stroke
(loading) direction were removed. The same
contact constraints were used as in the 600N
latch abuse analysis, including inactive, glue,
and touch. A distributed force of 4900N was
applied across the roll pin in the latch stroke
direction. The material properties for the
latch analysis were set as in Table 1.
Test
Material Properties
Clamp Body
ZA-8 – Zinc
Roll Pin
1010 – Steel
Receiver
4130 – Steel
Hook
12L14 – Steel
Table 1 – Material Properties
As in the nonlinear abuse analysis, the solver
was set for contact bias at 90% and Coulomb
friction was activated. To meet the 4900N
load, more expensive materials had to be used
for this customer than before. For example,
the receiver had been made of plastic, as it
is for many other customers. However, the
4900N load requirement is significantly
higher and required changing the receiver
from plastic to steel. This increased material
and process costs.
Since the earlier system had passed all of the
requirements, it was possible that the use of
a steel receiver was over-engineering. Using
simulation, it was relatively easy to compare
the customer’s earlier design to the current
version. By comparing the ultimate strength
of the earlier system to the new design, the
4900N requirement was determined too
severe. By changing the receiver from steel
back to plastic, the new design was as strong,
if not stronger, than the earlier system, and
a competitive price point was maintained.
ASC’s product development processes are
expanding. In the past, normal operating
conditions were the focus. However,
customers are now asking which parts might
fail under extreme conditions. When a
mechanism fails a physical test, it can be
embarrassing for the engineers and troubling
for the customer. By using SimDesigner for
CATIA V5, designers and analysts share one
common interface and database. Multiple
iterations can be virtually tested in the
computer without building anything and
investing in tooling. Failures and iterations
occur virtually, are fixed virtually, and then
when the best design is identified, verified
with physical testing.
Moving from the old school of ‘design,
build, test, break’ to ‘design, analyze, and
confirm,’ ASC engineers identified and
addressed the failure points in the handle
without going through several stages of
physical prototyping and testing. Physical
testing is becoming the last step for
verification. Using embedded analysis tools
earlier in the design process, ASC’s design
engineering team was able to determine weak
areas in the initial design before physical
prototyping and testing, saving a substantial
amount of time and money. α
On the Web:
www.ascglobal.com
simdesigner.mscsoftware.com
www.marc.mscsoftware.com
[7]
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Page 8
[ Case Study ] Casio
A WLP application example for a semiconductor
Fatigue life analysis for solder joints
Heat-stress analysis and thermal resistance analysis
New Possibilities through Simulation
Casio
Improves Digital Products
with Innovative Ideas
and VPD Technology
Cutting-edge products – and companies – are
often born of the latest advances in electronic
components. Take, for example, the nowubiquitous calculator. The year is 1957, and
although gigantic computers occupying entire
rooms have come on the scene, mechanical
calculators are still the standard for general
use. A small Japanese company started by
Tadao Kashio develops the world’s first
compact, fully electric calculator, the 14-A,
using relays for calculating elements, and
Casio Computer Co., Ltd. is born. From
that day, Casio has gone on to develop
and commercialize many new products
that apply unique concepts and make the
most of digital technology.
Just 10 years after the 14-A was introduced,
Casio created the AL-1000, the world’s first
software programmable calculator. Widely
used for scientific, technical, and business
This article was provided by the Tokyo office
of MSC.Software Ltd. The Casio sales
account representative is Takeshi Ohnishi,
Eriko Asakura wrote the story, and Reiko
Ishizuka provided the translation.
[8]
MSC.Software
calculations, it became a record long-selling
product. In 1972, Casio added scientific
functions to the personal calculator, giving
birth to the scientific calculator.
The list of Casio’s electronic and digital
innovations is a long one. Consider the
LCD (liquid crystal display) panel, which has
become an indispensable interface between
man and machine. One of Casio’s specialties
is small- and medium-size LCD panels for
mobile devices.
Casio has also brought its expertise and
innovative approach to another advanced
area – semiconductor after-processing, the
finishing of semiconductor parts for various
applications. In order to realize miniaturization, increased functionality, and cost
reduction for their then-primary product,
calculators, the company set up a subsidiary,
Casio Micronics, in July 1987 to carry out
this after-processing. Today Casio Micronics
conducts bump processing to create microelectrodes for bonding large-scale integration
chips to boards, along with TCP, Wafer Level
Package, and other mounting operations.
Under the guiding philosophy of “creativity
and contribution,” Casio develops a wide
range of consumer products, such as the
world’s first Global Positioning Satellite
(GPS) watch, the Satellite Navi, as well as
electronic devices to mount on system or
electronic equipment. Digital cameras and
watches, electronic dictionaries, cellular
phones, and electronic devices are Casio’s
main products for the next generation.
Casio’s business is centered on electrode
processing for LCDs and production of
film substrates, in addition to producing
packages for power supply chips, flash
memory, and other types of chips. Casio
Micronics’ expertise includes sputtering,
photolithography, etching, plating, and
other chip production technologies.
These are applied to produce a wide range of
high-precision mounting devices, such as gold
bump, solder bump, wafer-level chip-size
packages, and film devices, all of which play
vital roles in chip industry post-processing.
The Advanced Packaging Technology Group
in Casio Computer’s Core Technologies R&D
Division creates device packages that are used
by other groups within Casio. The group’s
main task is to develop the process, material,
and structures of Wafer Level Packages
(WLPs), using MSC.Marc for WLP heatstress analysis, fatigue life analysis for solder
joints, and thermal resistance analysis. In the
past, development of WLP structures required
many physical tests because of the numerous
structural parameters, but simulation
technology has enabled optimization with
fewer tests. In addition, since WLPs are
extremely small, it was almost impossible
to analyze their internal behavior. Using
computer simulation, Casio analysts can
now visualize what is happening within each
component material, such as stress
concentration, making it possible to quickly
take measures to improve the design.
“Simulation is no longer a complementary
phase of the design process, but a main
part of it,” says Tomio Matsuzaki of Casio
Computer’s Advanced Packaging Technology
Group. “We have entered a new age where
simulation technology leads the design. A
company’s future will depend on whether
simulation is utilized effectively. I have
high expectations for the progress of
computer-aided engineering.”
“We have entered a new age where simulation
technology leads the design. A company’s future will
depend on whether simulation is utilized effectively.”
visual presentation using simulation results
of features and structures is very effective.
For example, an MSC.Marc Mentat analysis
result can be shown during a meeting with
a customer in order to report results of an
analysis or as part of a proposal. Some major
semiconductor manufacturers have shown
interest in Casio Micronics’ WLP simulation
technology. Casio’s customers now recognize
that simulation is actually a part of the manufacturing process.
Takashi Awaya of Casio Micronics’ Marketing
& Engineering Department, WLP Business
Unit, says, “We have a unified system for our
business activities, but new systems are also
being introduced as we expand our business.
Technical Support and Marketing Tool
Casio Micronics uses MSC.Marc Mentat
as a technical support tool for their WLP
manufacturing process, creating structural
designs for both test models and actual
products and then verifying their reliability.
During design, MSC.Marc Mentat is used for
heat-stress, thermal resistance, durability, and
fatigue life analyses. By replacing physical
tests with computer simulation, significant
improvements have been made in terms of
cost and turn-around time.
Simulation is also used to evaluate new
structural designs or materials within Casio
Micronics, and is becoming increasingly
important. When compared to conventional
ceramic or resin packages, the most significant features of WLPs are ‘light, thin, short
and small.’ Since WLPs cannot be described
as an extension of an existing technology, a
Tomio Matsuzaki
The WLP business requires that many semiconductor manufacturers design and manufacture optimal packages for various devices
with quick turn-around time. Therefore,
connecting the various design systems
including simulation software is an important
task. It is still a common belief in the semiconductor industry that product reliability
largely depends on data based on physical
tests in order to assure accuracy,” Awaya continues. “I assume that turn-around time and
design quality will improve when engineers
who are more experienced in physical tests
start to utilize CAE.”
Meeting Future Challenges
Casio currently uses MSC.Marc for plastic
analysis to evaluate fatigue life of solder
joints, and plans to introduce creep analysis
for dropping or bending, which are
mechanical phenomena. At Casio Micronics,
Awaya believes that simulation should be
applied to the manufacturing process in the
future to improve the process itself and solve
issues such as minimizing material costs.
Since WLP is a new technology, not many
semiconductor manufacturers or test houses
have the environment to evaluate mounting.
If Casio Micronics is to support them in this
area, computer simulation will be essential to
utilize their rich analysis experience and lessen
the burden on their customers.
Casio has continued to win people’s
loyalty to their products, such as the
G-Shock shock-resistant watch, solar-powered
radio-wave watches, digital cameras, and
camera-equipped cellular phones. With VPD
tools as an essential part of the development
process, Casio intends to continue to meet
the challenge of creating the most advanced
and innovative products in the world. α
On the Web:
www.casio.com
www.casio-micronics.co.jp/en/
Takashi Awaya
[9]
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Page 10
[ Case Study ] Audi
[ Case Study ] Audi
CAE Data Management
Simulation data and process management is gaining momentum in
manufacturing today. More companies are developing systems
such as Audi’s CAE-Bench, based on MSC.Software’s
simulation data management solutions. Such
systems off-load routine tasks from
analysts, streamline the process of
getting and providing
consistent data within the
different development
phases and between
teams, and organize
the growing amount
of simulation data.
at
In the automotive industry,
there is the vision in every car
project to perform only the legally prescribed
real crash tests and to lower development
costs by drastically reducing the number of
hardware prototypes. Therefore it is necessary
to increase the number of virtual crash tests.
But the crash discipline is only one example;
the situation is the same for almost all other
fields of numerical simulation. In addition,
simulation offers the possibility to improve
the functional characteristics of the cars by
using stochastic, genetic, and other
optimization methods. The consequence of
this is a significant increase in the number of
simulation runs and results data.
• Functional dimensioning of doors,
flaps, and hoods
• PowerNet (simulation of the on-board
supply system)
Disciplines in CAE
All of the analysis disciplines listed below
require a large number of numerical simulations:
Trends in the automotive industry show
an increasing number of:
•
•
•
•
•
•
•
•
•
•
• product variants (USV, MPV)
• boundary conditions (government
regulations, technologies)
• statistical verification (stochastic
simulation) and
• multidisciplinary optimization
(discipline combinations).
Front, rear, side crash
Insurance testing
NVH analysis (Noise, Vibration, Harshness)
Head impact
Occupant safety (OS)
Pedestrian protection
CFD aerodynamics
Durability and fatigue
Stiffness of components
Global and local dynamic stiffnesses
This article, authored by Dr. K. Gruber,
Dr. U. Widmann, J. Reicheneder, and J.
Eberfeld of Audi AG (Ingolstadt, Germany),
originally appeared in Benchmark, the official
publication of NAFEMS. It has been
excerpted here.
Pre-processing
Applications:
PMD/CAD
Increasing product diversification, sharper
quality requirements, higher market
competition, more cost pressure, and shorter
development cycles were the driving forces for
the breakthrough of numerical simulation.
The numerical applications cover nearly all
of the virtual development process.
The result is once again a drastic increase
in the volume of numerical simulations.
On the other hand, the cost of CAE
simulation is falling because of advancing
hardware and software power (Figure 1).
Solving
Post-processing
Computer
Solver:
Audi AG
New Directions and Capabilities in CAE
Pre-processing
• Functional analyses can be performed faster
and earlier in the development process.
• More cost-effective and systematic analyses
can be performed.
• Deeper transparency is needed and thus
demands on documentation are higher.
MSC.Nastran
Simulation Costs
(Source: General Motors)
1960
2000
$30,000
$0.02
CAE Engineer
vs. System Costs
(Source: Detroit Big3)
Engineer
$36/hr
System
$1.5/hr
Number of CAE
Simulations
Cost of Physical
Prototyping
Mainframes
Workstations and Servers
Cost of CAE
Simulation
1960
Years
2000
Post-processing
Programs:
Ansa, Medina,
Scripts, vi-Editor
Animatior, Evaluator,
Pamview, FeGraph,
Scripte
Load Cases
Figure 2
An intensive and efficient use of numerical
simulation is only possible if we succeed
in rationalizing the process of numerical
analysis. Therefore consistent data
management is needed, which enables fast
access to simulation data and efficient
handling of huge amounts of data.
Audi CAE Process
The consequences of these trends can be
represented as follows:
Pamcrash,
Nastran,
Powerflow,
Kuli, Saber,
ManaSoft
In principle, the CAE process can be
divided into the respective sections of
pre-processing, solving, post-processing,
and reporting (Figure 2).
In the pre-processing step, the data of
the different car components are extracted
out of the CAD data management system.
Dependent on the analysis discipline, these
geometries are meshed according to certain
guidelines and mounted together with
barriers (crash) and dummies (occupant
safety) to a virtual car assembly, the so-called
numerical model. In addition to the
geometry, the physical parameters
(e.g., contacts and velocities) and the
material properties have to be defined in
the input deck. In these work steps different
pre-processing applications are used.
In data management the input data and all
metadata describing the car project and the
specific computer run (discipline, load case,
analyst) are stored.
The ‘solving step’ is the numerical solution
of the load cases defined in the input deck.
Important for data management are the
results (output decks) and additional
information (computer time, data volume
of the output, etc.).
The most standardizable section is the postprocessing. In this step the post-processing
objects (PPOs), e.g. curves, pictures, movies,
etc., are generated using different postprocessing applications. The PPOs, together
with the corresponding metadata, are stored
in the data management system.
In the reporting, the last step of the process,
the report is generated out of the previously
produced PPOs.
Project Demands for a CAE Data
Management System
In addition to the boundary conditions
resulting from the existing workflow at Audi,
the following requirements were identified:
• Because of the enormous number of simulations,
the data management system has to be able
to handle the huge amount of data.
• The representation of the data has to be
adaptive to fit the requirements of the
different disciplines and analysts.
• The concatenations of the objects and
data must be unique so that afterwards
the workflow can be reconstructed and
traceability is possible.
• Easy and fast access to the results with
competent preparation of the representations is required.
• To avoid routine jobs for the analysts,
an automatic standard evaluation and
reporting capability is necessary.
• To guarantee independence of the
computer hardware and operating system
and to economize the resources (CPU and
storage) of the user, a server-based Web
application should be employed.
• Automatic pre-processing with a link
to the CAD component database should
be realized.
The development of Audi’s CAE-Bench
system began in November 2001 and
was completed in December 2003. As of
February 2003, productive use of the system
began, along with expansion and adaptation
and the introduction of further disciplines.
Features of CAE-Bench
Input Deck
Solving, post-processing, importing in
the database, and reporting need to work
automatically. Thus it is important to
declare all the necessary information in
the input deck.
Storyboard
A central part of the post-processing in
CAE-Bench is the storyboard concept.
The storyboard is the complete definition
of a post-processing object (e.g., curve,
movie, etc.).
Representation of the Evaluation
The complete representation of the results
takes place in the Web browser. The browser
Figure 1
[ 10 ] MSC.Software
Volume 5 | Spring/Summer 2005 [ 11 ]
5/25/05
2:58 PM
Page 12
[ Case Study ] Audi
Future MSC.SimManager
Releases Will Deliver Standard
VPD Process and Vertical
Application Portal Solutions
window is divided into two frames. On the
left side there is a navigation frame and on
the right side the listings of the appropriate
PPOs are arranged (Figure 3).
Report
The report is generated automatically on a
master report that is declared in the input
deck. CAE-Bench provides a report editor
with multiple editing functions for handling
PPOs, i.e., adding, deleting, replacing, and
comparison of variants. The report in the
Web browser has proved itself in meetings
and presentations. In addition it is possible
to create a PDF (Portable Document File).
As the Audi CAE-Bench case study illustrates, managing
ever-increasing amounts of simulation data, and the simulation
process itself, is a critical issue for manufacturers today. For
the answer, many of them are turning to MSC.SimManager.
Figure 3
Advantages
Data Volume
One of the greatest benefits of Audi’s CAEBench system is the overall time savings. We
assume a time savings per simulation of about
one hour. With 100 simulations per engineer
per year and 50 engineers, we get 5000
simulations per year. The time saving for
this example would be 5000 hours per year.
This corresponds to three man-years. Thus
the simulation engineer can perform more
simulations, has more time for analyses,
can get the results faster, and therefore has
a better technical understanding.
5 sim./day
10 sim./day
15 sim./day
7000
6120
6000
6 Terabyte / Year
at 15 Sim. / Day
Data Volume [GB]
5000
4060
4000
Conclusion
3000
2040
2000
1000
Additional CAE-Bench benefits include:
• Standard information is extracted from
the solver output files automatically.
• Information is accessed via Web-GUI
(graphical user interface).
• Information is used for reports
and comparisons.
0
1
2
3
4
5
6
7
8
9
10
11
12
Time [Month]
Figure 4
PMD/CAD
Pre-processing
Solving
Post-processing
Challenges
The next challenge is computer-aided
integration. Product definition is based
on geometric design, functional design,
and physical verification. Product lifecycle
management is based on CAD data
management, configuration management,
component management, and logistics.
Simulation data management fills the
gap between CAE and computer-aided
testing (CAT) data management. Its basis
is CAE/CAT data management and
CAx integration.
[ 12 ] MSC.Software
Information
Management
Distributed
Databases
CAE-Bench provides many options and
challenges. The first challenge is the growth
in data volume (Figure 4). For instance, a
typical EuroNCAP calculation generates
approximately 2 Gbyte of data. In addition,
future conditions will push the data volume
even higher. We anticipate an increasing
number of engineers, number of simulations,
types and sizes of simulations, and types and
sizes of tests.
• Encryption of data for collaboration
with suppliers
• Standardized data representation
• Integration of applications (tools)
• Integration of different frameworks
• CAD integration and pre-processing for
distributed data grids
• CAT integration for distributed data grids
• Knowledge discovery and data mining
AUDI
VW Group
External Engineering Companies
External System Developers
System Suppliers
World
Transparency
Access Control
Inquiries
Reliability
Search
Load Balancing
Notifications
Accounting
Figure 5
One of the tasks in the next few years
will be the CAE integration of the different
companies in the group including external
engineering companies, system developers,
and system suppliers. This requires access and
search capabilities on distributed databases for
global information management, i.e., a
wide-area CAE network (Figure 5).
Global Data Grids
Global data grids enhance simulation data
management and the simulation workflow.
Referring to this we identify the following
requirements and considerations:
• IT infrastructure for distributed
engineering data grids
• Data sharing, data exchange, distributed
data, and databases
• Security of data and data access
Effective rationalization can only be achieved
through the analysis of the disciplinedependent CAE process. CAE-Bench
provides standardized evaluation and
archiving of key results and descriptive
documents. It is an open system based on
MSC.Software technology. The next activities
will be the extension of the process chain by
pre-processing, the development of concepts
for CAx integration, and the establishment of
global data grids.
At Audi, CAE-Bench has been in productive
use for more than a year. The system fits
our demands. Staff members are relieved of
standard operations and now have additional
time for specific considerations. α
References
1) “Doing the Right Thing First,”
MSC.Software Focus, Volume 1,
Spring 2003, pp 8-12.
2) Elberfeld, J.: “SDM – Integrated Data
Management for the Optimisation
of Computation and Simulation
Processes,” MSC.Software Focus
European Edition, Volume 1,
Spring 2003, pp 4-7.
3) Gruber, K.; Widmann, U.; Reicheneder,
J.; Elberfeld, J.: “CAE Data
Management at Audi AG.” Presentation
at MSC.Software EMEA VPD
Conference, November 2005.
MSC.SimManager is a Web-based environment that manages and
automates simulation processes, manages all associated data and
data history, and increases efficiency and innovation by delivering
product performance knowledge earlier in the product
development cycle. MSC.SimManager improves quality by
ensuring best-practice simulation processes and full traceability
of all input parameters, and increases productivity by greatly
reducing the number of manual tasks required. This gives
engineers more time to make and evaluate design decisions,
and further improves the return on investment from existing
simulation tools.
Using MSC.SimManager from their desktop, engineers are able to:
• quickly perform interactive and automated simulations,
• collaborate with colleagues across the enterprise,
• establish trends from previous data,
• evaluate design changes, and
• generate comparative reports.
By enabling a managed, repeatable engineering process,
MSC.SimManager helps ensure optimal product performance
and efficient product development.
MSC.SimManager consists of a hierarchy of Web portal solutions.
MSC.SimManager Portal Server is the base module that provides
the infrastructure for managing simulation processes and data,
including content and context management, application
encapsulation, the Web-based user interface, and tie-ins to
enterprise software.
With the next MSC.SimManager release, in summer 2005, a
standard VPD process portal will be provided. Data models,
material properties, meshes, load cases – all the steps throughout
a typical CAE process will be automatically defined. A subsequent
release slated for late 2005 will provide portals pre-configured for
specific attributes within major discipline areas for automotive and
aerospace applications.
These new portals will capture industry best practices and can be
further configured to suit company-specific processes. In addition,
they will help speed deployment of MSC.SimManager throughout
an enterprise.
Stay up-to-date with the latest MSC.SimManager developments at
simmanager.mscsoftware.com.
4) NAFEMS Seminar, “Die Integration
der numerischen Simulation in den
Produktentwicklungsprozess,”
Wiesbaden, Germany, 2003.
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Page 14
[ Case Study ] Invernizzi Presse
[ Case Study ] Invernizzi Presse
Invernizzi Presse
Gains Precision and Safety
with VPD Tools
With more than 40 years’ experience in the construction and development of
mechanical presses, the manufacturer Invernizzi Presse from Pescate LC in Italy
produces some of the safest and most technologically advanced presses offered
on the market today. In addition to their standard mechanical presses, Invernizzi
Presse offers custom-made presses designed and built to meet the needs of
individual customers. Invernizzi’s broad product portfolio, high-quality materials,
and technological expertise meet the industry’s stringent requirements for safety,
robustness, functionality, versatility, and durability.
Solving a Pressing Problem
About five years ago, the company performed a benchmark of different finite
element method (FEM) software packages to find the best analysis tool. “I studied
the principal providers of FEM software,” says Luigi Piccamiglio, engineer in the
research and development department at Invernizzi Presse, “and decided on
MSC.Marc because it is the best solution for our cases. We needed to study an
assembly of parts that are in contact with one another. MSC.Marc is a very good
product to study contacts and the thermo-mechanical behaviour of these parts.”
Another reason Piccamiglio chose the MSC.Software product was its preprocessor,
MSC.Patran. “We use MSC.Patran for meshing the models and it fits perfectly
with MSC.Marc.”
Applications and Customization
Invernizzi Presse now uses the combination of MSC.Marc and MSC.Patran
in a variety of applications, including:
• Contact analysis between pivot, bearing, and connecting rods to evaluate the
flex/bending stresses in the pivot, the contact pressure on the bearing, and
the resulting rod stiffness.
• Contact analysis between the presses’ pivot, bearing and rod, along with the
backlash of the pivot, in order to understand the thermo-mechanical behaviour
of the bearing. Invernizzi engineers found that the heat generated by the friction
between the parts increased the temperature of the mechanical components,
breaking the oil film and seizing the mechanism. With this knowledge, the
design was modified to improve performance.
Evelyn Gebhardt is MSC.Software’s marketing
communications manager. She is based in
Marburg, Germany.
[ 14 ] MSC.Software
• Mechanical safety structure analysis. The MSC.Marc model allows engineers
to study the mechanical behaviour of the safety system used on all types of
presses. The analysis uses flexible contact elements and an external force
representing the oil pressure.
• Epicycloidal analysis (study of a multi-stage gear transmission system). This
simulation allows Invernizzi engineers to evaluate the stresses in complex gear
tested. “Manually, we could not study the
parts as precisely – we spent more time and
had less precision,” states Piccamiglio. “With
MSC.Marc we not only save a lot of time,
but the precision of the calculation is a lot
better since the FE method is more accurate.
Now I get good precision on the parts I study
and can try more design variants in less time.”
collaboration with MSC.Software has been
a fruitful one,” Piccamiglio says. “We might
also look into dynamic simulation with
MSC.ADAMS to study and optimize the
link-drive mechanisms. I expect the
integration of MSC.ADAMS and MSC.Marc
will bring many advantages to our
development process.” α
Piccamiglio notes that another advantage of
FEM with MSC.Marc is that it is easier to
select the right material and material structure
for each type of press. Analyses with different
materials can be performed easily so the best
type of material can be
chosen in less time.
On the Web:
www.invernizzi.com
www.patran.mscsoftware.com
“The virtual product development
approach with MSC.Marc offers
us many possibilities.”
systems in order to optimise the gear
dimensions, avoid gear failure during duty
cycles, and extend the life of the mechanism.
• Load calculation during the bending
process in order to understand the correct
force needed to obtain the correct bending
of the material.
Using the results of these simulations,
Invernizzi can demonstrate the functional
performance of a press without having to
build a physical prototype, illustrating to its
customers that the press will fulfill the
requested tasks. This is especially important
when a custom-made press is needed, since
the production of a physical prototype would
be impossible due to cost and time restraints.
In addition to showing customers virtually
how the press will work, suggestions for
custom-made presses can be based on the
analysis results provided by MSC.Marc
and MSC.Patran.
“The virtual product
development approach
with MSC.Marc offers
us many possibilities,”
Piccamiglio explains.
“We can change the
geometry of the
coupling and the material characteristics.
Since we can choose different types of
material, we could, for example, cut and
optimize the weight of one machine. Using
the analysis results, we can reduce the weight
of the structure and the thickness of the sheet
metal which we use to build the parts of the
press, and therefore significantly save costs on
production.”
Safe operation of Invernizzi’s presses is
another critical reason supporting the
use of simulation. “Recently we did a
thermo-mechanical analysis on a particular
press because its high speed could have
increased the temperature within the
connecting parts of the press and the
bearing,” Piccamiglio says. “A very high
temperature in this joint can cause big
problems. If there is contact between the
pin and the bearing, it is a very dangerous
situation for the press and its operators.”
“When we make a proposal to a customer,
we include images of the FEM analysis to
demonstrate the development,” Piccamiglio
says. “In addition, we specify that we use
MSC.Software products to develop our
presses. The images are very useful, because
they help to convince customers to buy
our products.”
In another case, Piccamiglio studied a
security system for a press. “This security
system is very important, because if the
press is working with a force higher than
the nominal force, this security system can
interfere and stop the press. If not stopped
on time, the press might break and not
function as predicted,” he explains.
Precision and Safety
Expanding VPD
Before using MSC.Marc, the development
department of Invernizzi Presse used
mathematical methods to do the calculations
for the presses. These methods were timeconsuming and less precise because only a
certain number of design variations could be
Invernizzi will continue using MSC.Marc
and MSC.Patran, and possibly other
MSC.Software products. “MSC.Marc
gives us confidence in our results and offers
a complete list of features. I am very satisfied
with the results of our analyses, and our
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2:58 PM
Page 16
Simulation Fuels Advanced
Energy Research
Even as oil prices spiral past historic levels and natural gas costs go nowhere but up,
global energy consumption continues to increase. A growing world population, along
with rising standards of living, is straining a system already overtaxed. In the U.S., the
disadvantages of dependence on foreign oil and environmental concerns over the use of
fossil fuels have been at the center of public policy and debate for decades. While there
is no single, simple fix for the situation, innovative science is key to the solution.
Dr. Moe A. Khaleel, laboratory fellow and director, Computational Sciences and
Mathematics Division at Pacific Northwest National Laboratory (PNNL), has immersed
himself in finding the answer to these energy issues. Located in Richland, Wash., PNNL
is one of nine U.S. Department of Energy (DOE) multi-program national laboratories.
Managed by the DOE’s Office of Science, PNNL is operated for the DOE by Battelle,
one of the largest and most diverse energy research and development organizations
in the world.
Dr. Khaleel joined PNNL in 1993. He received his B.S. in engineering from
the University of Jordan in 1986, and master and doctoral degrees in structural
engineering from Washington State University in 1988 and 1992, respectively. Named
a laboratory fellow at PNNL in 2001, he conducted research on advanced materials
for transportation applications before turning his attention to world energy needs.
Along with establishing PNNL strategies for scientific and high-performance computing
and overseeing an internal research initiative dealing with computational mechanics,
Dr. Khaleel is actively involved in research on solid oxide fuel cells (SOFC), a low-cost,
clean alternative to fossil fuels. He is the national coordinator for the modeling and
simulation of SOFC as part of the Solid State Energy Conversion Alliance (SECA).
His research activities focus on continuum-level electrochemistry, degradation
mechanisms, and developing computational electrochemistry, fluid dynamics, and
mechanics tools for SOFC material/stack design and life prediction.
While finite element analysis using MSC.Marc in SOFC development was already
in place at PNNL, MSC.Software was brought in to create a graphical user interface
(GUI) customized for SOFC analysis, providing for automatically generated, detailed
3D models and easy parametric and material studies. The project also incorporated
PNNL-developed electrochemistry routines into the software.
As a result, advances in SOFC design and development that were previously unimagined
are now possible, and the technology looks even more promising. Dr. Khaleel recently
sat down with Alpha editor Carrie G. Bachman to discuss the advantages of solid oxide
fuel cells, the challenges of developing them, and how simulation continues to move
the research forward.
Photos by Jeff Rickey
Alpha: Many people don’t spend much time
thinking about global energy problems, at
least until they have to fill up their car’s gas
tank or pay their monthly heating bill. That’s
when the issue becomes personal. From an
industry perspective, what are the challenges?
[ 16 ] MSC.Software
Khaleel: The most visible industry that’s
impacted is the automotive industry, which
faces two major challenges. The first is
environmental, regarding CO2 emissions
from vehicles. For every 1,000 pounds of
vehicle weight, about 100 pounds of
CO2 are emitted over the vehicle’s lifetime.
The second is the issue of fuel consumption
and sufficient energy supplies. The industry
attempted to address energy efficiency
through a joint partnership between
industry and the U.S. government called
the Partnership for New Generation
Vehicles. Hybrid vehicles, in which an
internal combustion engine is supplemented
with batteries and other electrical supplies, are
actually an offshoot of that initiative.
That program made some, but not sufficient,
progress, so a new initiative called
FreedomCAR has been created.
Its primary goal is freeing people from
dependence on foreign oil and pollutant
emissions. That initiative is targeted at
building next-generation vehicles powered
by hydrogen, with fuel cells as the main
drivetrain in these vehicles.
In all of these initiatives, the major driver is
fuel consumption. There is a big gap between
the amount of oil we in the U.S. produce
daily – less than eight million barrels – and
what we consume daily, which is on the order
of 16-20 million barrels a day. Sixty percent
of what we consume, we import, and it’s only
increasing. By 2020 that gap will be growing,
and it’ll be on the order of tens of millions of
barrels daily.
These issues – fuel consumption and
environmental impact – affect all industries.
In the trucking industry, for example, the
majority of fuel consumption happens during
idling at truck stops. That takes about
100,000 miles off the life of the engine, and
a Canadian study showed that idling costs
about $60 CDN per day. Fuel cell technology
could be used for these ‘auxiliary power needs’
when they’re not being used to propel the
truck. There are initiatives by the major
trucking companies and some engine
manufacturers to develop what they call the
‘More Electric Truck.’ It still has an internal
combustion engine, but replaces belt-driven
systems with electrical components. By using
a fuel cell to provide the auxiliary electrical
needs, fuel consumption could be cut by
10%. That’s huge. In addition, the trucks
would be driven at their maximum efficiency
because the engine would be operating at its
maximum efficiency, since all other needs are
driven by the fuel cells. Likewise, if you go
the route of the hydrogen-powered car with
fuel cells, there would be literally no
emissions. What comes out of the tailpipe
would be water.
In the aerospace industry, when you board
an airplane, they normally run a turbine to
provide air conditioning while on the ground.
This is fairly fuel-intensive. Using fuel
cells for this auxiliary power supply would
consume only about 60% of the fuel that
a turbine consumes. NASA and Boeing are
pursuing fuel cells for auxiliary power needs
when the airplane is parked and also
during flight.
There are other industries outside automotive
and aerospace that suffer from energy
problems. Take, for instance, the crisis in the
Northeast in the summer of 2003, when a
fuel fault in the system, along with a number
of mistakes, cascaded and resulted in a
widespread outage. One way to provide for a
more reliable system, and frankly, a more
secure system, would be to generate electricity
in a distributive manner using fuel cells.
Fuel cells also have benefits on an individual
level. Instead of using a heat pump in your
house, you could use a fuel cell to provide all
of the electrical needs for your house so you
don’t have to draw anything off of the grid.
When you’re not home, the fuel cell is still
working, and you could sell electricity to the
grid. Banks and stores and so forth could do
the same thing. That’s something I think is
fairly important.
The point is, we need to look for alternative
routes to meet our energy needs in each industry.
“By adding
electrochemistry
capabilities ...
MSC.Marc becomes a
very powerful tool.”
candidate for propulsion of automobiles,
operates on hydrogen fuel. However, if other
species in the fuel stream mix with the
hydrogen, the fuel cell could be poisoned.
You either have to have pure hydrogen
onboard the vehicle, or you have gasoline
and go through a reforming process. There
are issues with onboard reforming and many
of the automotive companies are not in favor
of it today.
Solid oxide fuel cells are high-temperature
fuel cells. They run at 700 degrees Celsius
while PEM fuel cells run at 120 degrees C.
On the outside, the systems look the same
but the beauty of the solid oxide fuel cell is
that it’s fuel-flexible. When you reform
gasoline you get hydrogen and carbon
monoxide and so on. CO2 can be used in the
solid oxide fuel cell. It will be converted to
hydrogen and utilized. Also, with solid oxide
fuel cells, you could do ‘on-cell reforming’
where you have methane or hydrocarbon
fuel that a PEM fuel cell couldn’t take,
but it comes into the solid oxide fuel cell
and gets reformed right on the cell itself.
So it’s very forgiving.
Alpha: It doesn’t poison the fuel cell if there’s
something else in the flow?
MK: That’s correct. Another problem with
PEM fuel cells is water management. This
issue is nonexistent in solid oxide fuel cells.
Both produce water, but with the PEM fuel
cell, a lot of the conductive properties of the
cell depend on the level of water. You have to
add water in the vapor in the PEM fuel cell
with hydrogen to make sure that the
membranes and so on continue to function,
while in the solid oxide fuel cells you don’t
have to do that at all.
Alpha: In an industrial application, are
SOFCs used in stacks?
MK: A five-kilowatt fuel cell actually consists
of multiple cells that are stacked vertically.
The current state-of-the-art is what’s called a
‘flat plate design.’
Stacking arrangement of layers in CAD-generated
SOFC example.
Alpha: What is it about the solid oxide fuel
cell that is so promising?
MK: There are several types of fuel cells –
proton exchange membrane, or PEM fuel
cells, molten carbonate, alkaline, solid oxide
fuel cells. Each one of them has certain
operating conditions, such as temperature
ranges and the type of fuel they will accept.
The PEM fuel cell, which is the most likely
Solid oxide fuel cells are not new.
Westinghouse has demonstrated them for
many years. The main issue is cost. To bring
the cost down, you need to have mass
customization. You need to look at modular
designs and high power-density fuel cells. The
high power-density fuel cells are flat plate
designs, so you take one and stack the next
one, the next one, the next one, and that’s
how you get to five kilowatts.
Alpha: What are the challenges in designing
and testing a fuel cell?
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2:58 PM
Page 18
Alpha: So what are the drivers behind
modeling and simulation in fuel cell development?
Parametric SOFC
Post-processing contour plot
“...a finite element framework is very flexible.
You can make design changes and see [their]
impact on performance and safety.”
MK: There are many. The first challenge is
in the materials. The whole idea is to come
up with a ceramic cell material that provides
the highest power density and is very stable.
Then the cells have to be sealed. There is a
rigid seal made from glass, so we consider its
stability and other characteristics to be sure it
is durable, won’t crack, and so on. There are
also flexible seals made of mica. The leak rate
out of these has to be acceptable and they
need to accommodate air between the bulk
of the cell, which is metal, and the cell, which
is ceramic. The thermal mismatch between
the cell and the metal causes the materials
to impart stresses on one another, so the right
accommodation of air is needed. In addition,
these materials operate at very high
temperatures, so material will migrate and
move from one spot to the other. We want
to make sure that they don’t move from a
favorable spot to an unfavorable spot. We
also want to reduce the use of noble metal
in these fuel cells.
Thermal management is a critical issue.
Because there are electrochemical reactions
happening within the cell, heat is generated
and must be dissipated in order to avoid hot
spots and so on. We don’t want some cells
with very low electrochemical activities and
others with very high electrochemical activities.
Finally, manufacturing cost is a significant
concern. We need lowest-cost manufacturing
techniques while maintaining quality to make
sure that the fuel cell operates as it is designed
to do. Getting fuel cells to the right cost level
is actually in favor of solid oxide fuel cells.
We’re able to use more commodity materials,
much cheaper materials, that I believe will get
us there. Much of this progress is due to the
SECA program.
[ 18 ] MSC.Software
Alpha: What is SECA?
MK: SECA is the Solid State Energy
Convergence Alliance, a program initiated
in 1999 by the U.S. Department of Energy
(DOE) Office of Fossil Energy. The goal is
to develop an environmentally friendly,
commercially cost-effective, and reliable
solid oxide fuel cell for a wide range of
applications. The DOE’s National Energy
Technology Laboratory (NETL) and PNNL
are responsible for program development.
SECA has two major components – industrial
teams and a core technology program. There
are six industrial teams, each led by one
company and drawing its membership from
other companies, universities, national labs,
and such. Teams are led by Siemens
Westinghouse, Cummins Power, Delphi
Automotive, Acumentrics, Fuel Cell Energy,
and GE Power Systems.
PNNL runs the core technology program,
which has six teams dealing with materials,
manufacturing, fuel reforming and
processing, power electronics, controls and
diagnostics, and modeling and simulation.
I’m the national coordinator for the modeling
and simulation team, along with Travis
Schultz from NETL. In the core technology
program, we look for the next technological
challenges and what we need to do to
overcome them. We engage universities,
national labs, industries, small business,
whoever can help with these activities.
SECA is a goal-driven alliance, which is
extremely important for its success. I honestly
believe this approach – working toward
established goals in an integrated fashion
– will make a big difference.
The second is stack design. There are many
issues associated with trying to optimize flow
design, finding the best flow possible to
remove unneeded heat so there are no hot
spots. But at the same time, we want to
maximize electrochemical activities so we get
the highest power density possible in these
fuel cells. Above all, we want to make sure
stresses don’t build up and lead to the cell
breaking down. We also need to understand
how potential degradation mechanisms –
thermal fatigue, degradation of the interfaces,
material creep – can be avoided.
The third activity is using modeling and
simulation broadly to set requirements for the
different components. There is the exterior
system, the stack, the heat exchanges, the
reformers and so on, and we need to
understand the interactions between these
subcomponents. What is the stack required
to do? What is the flow rate, what will be the
concentration of the different species in the
fuel, what should the temperature of the
incoming air be, things like this. Those are
system-level modeling activities, and require
understanding not just the fuel cell, but the
reformer, and so on. We want to optimize not
just the performance in terms of output, but
also the life of these systems. We don’t want
a cell with extremely high performance but
a very short life.
The finite element [FE] framework really
fits the physics we need to study at the stack
level. What we’re trying to do is model the
flow, which in these systems is laminar flow.
There is no turbulence, and FE works
beautifully there. Another area is the heat
associated with electrochemical activities.
Again, that fits in the FE framework, and
the electrochemistry itself can be handled
with user-defined functions or routines.
After that we can calculate the stresses using
just the normal things that we do in the finite
element framework.
So for design purposes, a finite element
framework is a very flexible framework where
you can make design changes and see the
impact of these design changes on
performance and safety.
Air Flow
Air Flow
Fuel Flow
Air Flow
Fuel Flow
Air Flow
Fuel Flow
Air Flow
Fuel Flow
MK: First of all, we’re trying to get rid of
trial-and-error procedures. We want to guide
development activities, manufacturing, the
material development itself. When we
consider modeling and simulation, we group
its use into three activities. The first is
material design – looking at the qualities of
nickel, ceramic, how porous a material is,
what will provide the best behavior.
Fuel Flow
Simulating three different flow designs led to the unexpected discovery that a co-flow design (center) provided the
lowest temperature gradient and the highest power density.
Alpha: How has the use of simulation
impacted fuel cell design?
ultimately GM adopted the technology,
calling it quick forming.
MK: Well, for example, we ran simulations
on three different designs: cross-flow, in
which the fuel is going in one direction on
top of the cell, and the air is crossing under it.
In a co-flow design, the fuel is going one way
and the air under the cell is going the same
way. In counter-flow, the fuel is going one
way and the air is going the other. The
industry has been using cross-flow, but
based on the simulation results, we found
that the co-flow design provides the lowest
temperature gradient and the lowest
distressors. The co-flow design also gives
the highest power density possible. We
wouldn’t have been able to discover this
experimentally. It’s very difficult to see
what’s inside the stack. Through
simulation we were able to do that.
Alpha: What led you to use MSC.Marc
in fuel cell development?
Alpha: The primary Virtual Product
Development tool you use is MSC.Marc.
How did you first use it?
MK: We first started using MSC.Marc in
1992 to look at a new class of metal forming,
a superplastic forming of aluminum. It
suffered from what we call low forming times,
and by combining MSC.Marc and certain
internal tools that PNNL built for understanding material behavior, we were able to
come up with ways to make sure that the
forming time was reduced by more than an
order of magnitude, which made that process
suitable for low-volume automotive
production. We enhanced our materials,
came up with new sets of materials, and
MK: MSC.Marc is a multi-physics tool with
capabilities for flow, heat, mechanical stress,
and electrical modeling. By adding
electrochemistry capabilities and certain
enhancements to the existing flow
simulations, MSC.Marc becomes a very
powerful tool for us. In addition, the open
structure of MSC.Marc allows customization
– databases, user routines, and so on.
We’ve been working with MSC.Software to
design a graphical user interface [GUI] with
all the ‘smart’ in it, so we know the range of
parameters for different materials in terms of
thicknesses and dimensions and so on. We
also put in the right constrictive equations,
material relations based on extremely
thorough experimental studies done at
PNNL. One can easily extrude complex
designs that normally take engineers days to
build. The customized GUI allows you to
build the design or import it from any of the
major CAD systems, and the GUI is smart
enough to recognize the different material
sets. It allows all types of analysis, from flow,
thermal, and electrochemical to mechanical.
The next step is to look at the life of
the stack. Certain degradation will happen,
and MSC.Marc has capabilities to deal
with material creep. We are also about to
add capabilities to look at degradational
interfaces in terms of resistances so we can
enable long life.
Our goal is to use this customized MSC.Marc
tool to minimize degradation – not just
predict it, but minimize it, remedy it. But
to come up with remedies you need to
understand the root cause of why things
happen, where they happen, when they
happen. This enhanced MSC.Marc package
does that. It gives us viable designs very
quickly. We know that a design works and
how to make a fuel cell last for a long time.
Alpha: How was this done before
simulation tools?
MK: Only in an ad hoc fashion. There wasn’t
an integrated set of tools to look at it. You
addressed one part of the problem with this
tool, one part of the problem with that tool,
and so on. To make the discoveries we seek,
you really need all of these tools together.
Alpha: So will the work that PNNL and
MSC.Software are doing with MSC.Marc,
building the electrochemistry routines into
the customized GUI, be provided to SECA’s
industrial teams?
MK: Yes. We work with many software
vendors, and our assessment was that
MSC.Marc is the best tool for these
multi-physics activities. We embarked on
our relationship with MSC.Software in order
to build this tool, and to make it available to
all of the industrial teams to accelerate development.
Alpha: Obviously modeling and simulation
within scientific research and development
offers many advantages. In your experience,
how quickly is it being adopted? What
cultural issues does this new technology raise?
MK: I believe scientific discovery is enabled
by three main pillars – experimentation,
theory, and computing. Many discoveries in
the scientific arena are enabled by this
integrated approach, and I believe there will
be even more recognition of modeling and
simulation as we go forward.
I honestly believe there is still a culture where
the experimentalists work by themselves, and
the computing people work by themselves,
but certain institutions are trying to change
that culture. At PNNL, we talk about ‘system’
science, which means integrating multiple
scientific fields – chemistry, biology – within
that integrated approach of theory,
experiments, and computing. And computing
is really the underpinning of a lot of this.
Today we’re bringing the experimentalists and
the modeling people together. There’s a need
for a cultural change. α
On the Web:
www.pnl.gov
www.seca.doe.gov
5/25/05
2:58 PM
Page 20
The Principles of
Analysis in structural or mechanical
engineering means the application of an
acceptable analytical procedure based on
engineering principles. Analysis is used to
verify the structural, thermal, or other multiphysical integrity of a design. Sometimes, for
simple structures, this can be done using
handbook formulas or other closed-form
solutions. More often, however, this type of
analysis relates to complex components or
structural assemblies and is performed using
computational simulation, part of a Virtual
Product Development (VPD) approach.
at all points in the structure, and the stiffness
becomes a matrix of individual stiffness
components assembled from each element
in the structure. However, the underlying
principle is basically the same. Knowing
the force (or in some cases the prescribed
displacement) and the stiffness of the
structure allows the associated ‘unknown’
to be calculated. Most analyses subsequently
continue with downstream calculations to
derive associated measures such as strain and
stress, and then use these for performance,
design, or other visualization purposes.
The predominant type of engineering
software used in these analyses is based on
the Finite Element (FE) method, giving rise
to the commonly used term Finite Element
Analysis (FEA). Over the past 50 years, FEA
has been successfully applied in all major
industries, including aerospace, automotive,
energy, manufacturing, chemical, electronics,
consumer, and medical industries. FEA is
indeed one of the major breakthroughs of
modern computational design engineering.
Such structural calculations are of course
only valid where a linear relationship
between force and displacement can be
assumed to exist. That is, if one applies
twice the force, the spring will deflect twice
as much. In reality, all forms of structural
mechanics exhibit nonlinear behaviour,
whereby the stiffness of a structure
progressively changes under increased
loading, as a result of material changes
and/or geometric and contact effects. The
end result is that the force applied and the
displacement observed are no longer linearly
proportional. The simulation of such
behaviour characterises ‘nonlinear analysis’
and can be summarized by the equation
f ≠Ku. Both for mathematical and
computational convenience, early FE
calculations assumed that a linear structural
response was indeed a good approximation,
especially for the relatively small displacements (that is, relative to the structural
dimensions themselves) and the materially
elastic behaviour that were commonly
considered in structures such as buildings
and aircraft.
Origins of Structural Analysis
The origins of structural mechanics go back
to early scientists such as Isaac Newton and
Robert Hooke. All physics students learn
Hooke’s Law, as illustrated by a simple spring,
with stiffness K (N/m), and loaded at the free
end by a force F (N): Hooke theorised a
simple linear relationship between force
applied and the associated deflection, f ≠Ku.
Thus, the deflection (u) can be easily
calculated by dividing the force applied
by the stiffness coefficient.
This article is excerpted from MSC.Software’s
Introductory Guide to Nonlinear Analysis.
[ 20 ] MSC.Software
Today’s practical applications of such linear
systems are somewhat more complex, and are
solved by means of ‘matrix’ computational
methods. The force and displacements
become vectors, potentially containing entries
But as computational techniques have
evolved and computer hardware capacities
expanded, it is now increasingly common for
engineering designers to step closer to the
physical reality of their designs by including
nonlinear effects in their calculations. Indeed
many designs, such as automotive crash
structures, deformable packaging, or locking
and sealing systems, are completely reliant on
nonlinear behaviour in order to function as
intended. In these and many other cases,
the assumption of linearity is no longer
an acceptable approximation. Nonlinear
behaviour is also widely exploited in the
simulation of the manufacturing process
itself, with applications such as metal and
plastics forming, pre-stressing, and heat treatment.
In the 1960s, researchers began applying the
finite element method to non-structural fields
such as fluid mechanics, heat transfer, and
electromagnetic wave propagation. In fact,
many engineering and scientific computations
can be solved based on similar principles, that
is, the solution of differential equations by
setting up and solving systems of simultaneous equations. Theorists proved that in
general, provided some mathematical
conditions are met, the method converges
to the correct theoretical results. Around this
time, researchers also started applying FEA
to nonlinear problems.
FEA History
Characteristics of Nonlinearity
In the mid-1950s, American and British
aeronautical engineers developed the finite
element method to analyse aircraft structures.
Although the earliest calculations bore only a
passing resemblance to the FE method as we
know it today, the underlying principles of
discretisation (meshing), equilibrium
(internal/external force balance), and
constitutive modeling (materials) still
formed the basis of the calculations.
As already described, all physical processes
are to some degree nonlinear. Pressing an
expanded balloon to create a dimple (the
stiffness progressively increases, that is,
the rate of deflection decreases the more
squeezing force is applied) or flexing a
paper clip until a permanent deformation
is achieved (the material has undergone
a permanent change in its characteristic
response) are two examples. These and many
other common everyday applications exhibit
either large deformations and/or inelastic
material behaviour.
Discretisation (more commonly known
as ‘meshing’) refers to the way in which
a complex structural component can be
subdivided into a large but finite number of
relatively simple ‘elements.’ By forming the
stiffness characteristics of each individual
element and combining those together into
an interconnected system of simultaneous
equations, these engineers were able to extend
Hooke’s basic principles into a robust and
computationally efficient solution process.
Although somewhat limited in complexity
and restricted by the computational
equipment of the time, these calculations
formed the practical origins of today’s vast
array of FE-based technologies.
So where does nonlinear behaviour originate,
and how can we assess its significance? In
general there are three primary sources.
Material nonlinearity is the ability of a
material to exhibit a nonlinear stress-strain
(constitutive) response. Elasto-plastic,
crushing, and cracking are good examples,
but this can also include time-dependent
effects such as visco-elasticity or viscoplasticity (creep). Material nonlinearity is
often characterised by a gradual weakening
or softening of the structural response as an
increasing force is applied, due to some form
of internal decomposition.
Structures whose stiffness is nonlinearly
dependent on the displacement they
may undergo are termed geometrically
nonlinear. Geometric nonlinearity accounts
for phenomenon such as the stiffening of a
loaded clamped plate, and buckling or ‘snapthrough’ behaviour in slender structures or
components. Geometric nonlinearity is often
more difficult to characterize than purely
material considerations. Geometric effects
may be both sudden and unexpected, but
without taking them into account, any
computational simulation may completely
fail to predict the real structural behaviour.
Early FE analyses were typically performed
on single structural components that
underwent relatively small displacements.
However, when considering either highly
flexible components or structural assemblies
comprising multiple components, progressive
displacement gives rise to the possibility of
either self- or component-to-component
contact. This leads to a specific class of
geometrically nonlinear effects known
collectively as boundary condition or
‘contact’ nonlinearity. In boundary condition
nonlinearity, the stiffness of the structure
or assembly may change, in some cases
considerably, when two or more parts either
contact or separate from initial contact.
Examples include bolted connections,
toothed gears, and different forms of
sealing or closing mechanisms.
In the real world, many structures exhibit
combinations of these three nonlinearity
sources, and the algorithms that solve
nonlinear equations are generally set up to
handle this. To find evidence of possible
nonlinear behavior, look for characteristics
such as permanent deformations and any
gross changes in geometry. Cracks, necking,
thinning, distortions in open section beams,
5/25/05
2:58 PM
Page 22
LEGO Builds Quality and Safety Using VPD
load. At this stage the material is assumed
to be fully plastic and has lost all
engineering performance. Far from being
a disadvantage, softening of this nature is
specifically designed into the behaviour of
many ‘designed to fail’ components such
as safety enclosures in cars.
Since 1932, the LEGO Group has built a reputation for
delivering quality products and experiences that stimulate
children’s creativity. More than 1.4 million LEGO parts are
produced every hour, making up the 100 million LEGO sets
produced annually. With this many parts, every part and
every change, even small changes in material usage, have
a tremendous impact on costs. To validate products before
they go into production, the LEGO product development
team uses MSC.Marc, MSC.Patran, and MSC.Nastran
simulation software.
Updated Equilibrium Configuration
crippling, buckling, stress values which exceed
the elastic limits of the materials, evidence of
local yielding, shear bands, and temperatures
above 30% of the melting temperature are all
indications that nonlinear effects may play
a significant role in understanding the
structural behaviour.
Nonlinear FEA Concepts
For all FE analysis, it is important to
recognise that, whether linear or nonlinear,
the FE method is an approximation of reality,
the success of which is dependent on good
and balanced judgments on issues such as:
• The ‘quality’ of the FE model
(geometric accuracy)
• The discretisation process (choice, creation,
and distribution of the mesh)
• Material properties and related
assumed behaviour
• Representation of loadings and
boundary conditions
• The solution process itself (solution
method, convergence criteria, etc.)
It is also important to recognise that
nonlinear applications are inherently more
complex to execute than linear applications.
For example, the principle of ‘superposition’
(in which the resultant deflection, stress, or
strain in a system due to several forces is
simply the algebraic sum of their effects
when separately applied) is no longer valid.
Other linearising assumptions also require
examination for their validity, such as
the relationship between strain and
displacement, between stress and strain,
and the treatment of contacting bodies.
Although modern FE programs routinely
include a significant library of inherent
intelligence, diagnostics, and self-correction,
the analyst’s experience is still critical to the
success of a nonlinear analysis.
In nonlinear FEA, some or all of the following
‘linearising’ relationships may be violated:
• Small Strains
Most metallic materials are no longer
useful when the strain exceeds one or two
percent. However, some materials, notably
rubbers, other elastomers, and plastics, can
be strained to hundreds of a percent. Such
applications require a redefinition of
traditional measures of ‘engineering’
(or small) strain.
• Nonlinear Strain-Displacement
(Compatibility) Relationships
Applications involving large rotations
(even for small strains) can violate
traditional linear strain-displacement
relationships. In such cases the changes
in the deformed shape can no longer be
ignored. The physics of buckling, rubber
analysis, metal forming, and many other
common applications require that the
often-ignored higher derivative terms in
the strain displacement relationship be
incorporated into the formulation.
• Nonlinear Stress-Strain
(Constitutive) Relationships
Nonlinear constitutive relationships relate
to the progressive change in a material’s
response according to the amount of strain
it experiences. Plasticity is a very common
example. Initially characterised by a nearlinear response, plastic materials typically
reach a yield point after which their ability
to carry increased load is significantly
reduced. If the load is removed, the postyield strain level produces a permanent
material deformation. Under continued
loading, plasticity may progress until
displacements effectively become infinitely
large for an infinitely small increase in
Equilibrium is one of the underlying
principles of the FE method, and ensures
that externally applied forces and internally
generated states of stress are balanced. The
overall result of nonlinearity (from whatever
source of origin) is that the forcedisplacement relationship requires continual
updating in order to maintain equilibrium,
and hence the physical validity of the
simulation. Numerical equilibrium is typically
maintained by solving nonlinear applications
with an ‘incremental-iterative’ approach.
Incremental-Iterative Solution Procedures
Because FEA is an approximate technique,
the method used to solve the simultaneous
equations that describe the physics of any
application is an important consideration,
especially when the application is nonlinear
in nature.
In a simple linear analysis, a load is applied
and displacements are calculated from a
relatively simple inversion of the stiffness
matrix. In theory, the value of the load is
unimportant since the linearity of the
response and the principle of superposition
can be used to extrapolate to any desired
loading magnitude. In nonlinear analysis, the
non-proportionality between the applied load
and the resulting displacements is accounted
for by applying the load in a series of steps, or
increments. Early nonlinear analyses used a
purely incremental approach, but depending
on the size of the increments used and the
degree of nonlinearity encountered, such
techniques often diverged from the true
In today’s solutions, within each load
increment the loss of equilibrium between
load increments is corrected using an iterative
technique. The details of this process are
unimportant here; suffice that the subsequent
recalculation of internal stresses progresses
until the equilibrium balance is restored (in
practice a small out-of-balance is normally
tolerated subject to some convergence
criteria). Such methods are referred to as
‘incremental-iterative’ (or Newton-Raphson)
methods and are widely used. The computational aspects of nonlinear equation
solution have been subject to a great deal
of research, and most of today’s nonlinear
FE codes offer a number of alternative
solution procedures.
More than 300 engineers and managers develop new designs for the approximately
200 to 300 new parts designed each year. Maintaining state-of-the-art product
development tools is imperative. “The analyses that we do on plastic parts include
strength/stiffness, strength/thickness, and fatigue analysis,” says Jesper
Kjærsgaard Christensen, CAE consultant with LEGO. “Of course, the goal is to
ensure safety, as well as reduce material usage where possible or change from one
material to another.”
Nonlinear Dynamic Analysis
VPD technologies were implemented in a three-phase process. During the first
phase, LEGO benchmarked different FEM products, deciding on MSC.Marc,
MSC.Patran, and MSC.Nastran because of their features, ease of use, and technical
support. The second phase included training, along with comparing simulation
tests with known results to better understand how the software should be utilized.
The third phase included implementing structural calculations in the development
process and establishing an FEM team capable of avoiding structural problems in
LEGO tools and parts.
Incremental nonlinear FE solutions are often
termed quasi-static. Although the loading is
typically applied progressively in a number of
increments, this process is purely a numerical
convenience and does not represent the
structural response over time. Even where
creep or contact conditions are included,
strictly speaking the nonlinear model is
assumed to be ‘static’ (or at least ‘quasi-static’
in nature). In essence, the structural mass is
non-excitable (other than by gravity), and
velocity and other acceleration effects are
ignored. Structural behaviour in which time
effects are significant are referred to as
‘dynamic’ or ‘transient.’
For numerical purposes, it is convenient to
sub-classify dynamic FE applications into
‘modal’ or frequency-based problems and
those that are truly transient. Modal-type
applications use the frequency response of the
structure to model effects such as natural and
forced vibration. Although dynamic over
given periods, these calculations can be
simplified due to the ‘steady-state’ nature of
their dynamic behaviour. Truly transient
effects are dealt with using a dynamic ‘stepby-step’ procedure in which the FE solution
is progressed in a series of time steps.
The Finite Element Method (FEM) team at LEGO is responsible for virtual
development of parts and tooling, beginning in the conceptual development phase.
The objective is to focus on product safety, as well as reduce overall cycle time,
increase functionality of toys, and make material/structural knowledge available
to more people within the organization. By determining how a part will behave at
an earlier stage, there are fewer changes made to tooling, so the costs associated
with building a physical prototype and making changes to molds can be
substantially cut.
Safety testing conducted at LEGO includes compression, torque, tensile, and drop
tests, as well as tests for sharp points and edges. Examples of these tests include
linear stress analysis on a tool part for the 2x4 LEGO brick using MSC.Nastran and,
using MSC.Marc, contact analysis on the same part to define a more realistic
boundary condition. Additionally, MSC.Marc nonlinear analysis is utilized to
simulate a compression test on the 1x16 LEGO TECHNIC element. On this same
part, MSC.Marc can simulate a torque test or generate a force-displacement
diagram for contact analysis.
One of the many benefits LEGO Group has realized with VPD is improved design.
“We’re not afraid to try a new solution,” Christensen said. “With simulation our
designs have been more stable. Simulation provides an opportunity to try more
solutions and have the confidence that when you have a very strict schedule and
you come up with a virtual solution, it will work when it is made.”
Simulation has helped LEGO reduce the overall time from concept to finished part.
Another tangible benefit is the understanding of where stresses do and don’t occur.
With this knowledge, an engineer can make what might seem to be a very
insignificant change in mass, but which results in significant material savings – a
welcome reduction, especially for high-volume parts.
At the end of its two-year simulation implementation program, LEGO Group has
reduced its dependency on physical prototyping, eliminated costly changes to
tooling, and substantially reduced manufacturing costs, including materials and
service life of molds.
www.lego.com
[ 22 ] MSC.Software
5/25/05
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Page 24
Dynamic FE simulations may of course be
structurally linear in terms of geometry,
material response, or contact/boundary
conditions. However, where both transient
and nonlinear effects are significant, the
FE solution performed is termed
‘nonlinear-dynamic.’
Although in reality all applications are both
nonlinear and dynamic in nature, the analyst
may look to make linearising or static assumptions about the behaviour in order to
avoid such numerical complexity. Nonetheless, with improved FE technology and
faster and higher-capacity computational
systems, nonlinear dynamics analysis now
makes up a significant proportion of the FE
simulations performed. Automotive crash or
other impact applications are good examples
of situation in which both nonlinear and
dynamic effects are highly significant.
• Explicit Dynamics Methods
By contrast, an explicit approach advances
the FE solution without (or at least less
frequently) forming a stiffness matrix, a
fact that makes the coding and execution
much simpler. For a given time-step size,
an explicit formulation generally requires
fewer and less complicated computations
per time-step than an implicit one.
Some Practical Information
It is generally advisable to prepare
for a nonlinear analysis by starting with a
relatively simple model. Nonlinear behaviour
can be complex to interpret, so the gradual
addition of new sources of nonlinearity into
the model can help considerably with
understanding the results obtained. While the
final analysis should be executed with a
refined mesh suitable to capture the
nonlinearities involved, sample analyses
involving coarser meshes will also help keep
the investigative trial models to a practical
size and execution time.
Dynamic Solution Procedures
In some respects, the solution of transient
dynamics problems is a simple extension of
standard linear or nonlinear static problems.
The basic stiffness equations are augmented
with velocity, damping, acceleration, and
mass terms, and in addition to a spatial or
geometric discretisation, the time over
which the dynamic effects take place is
also ‘discretised’ into a number of time
increments. The FE solution is then
progressed through time in a step-by-step
manner, taking into account velocity and
acceleration response in addition to pure
force-displacement behaviour. Most
nonlinear dynamics FE codes offer one or
both of two major approaches to dynamic
equation solution, namely ‘implicit’ and
‘explicit’ methods.
• Implicit Dynamics Methods
An implicit approach solves a matrix
system, one or more times per step, in
order to advance the solution. It is
particularly appealing for a linear
transient problem, since it allows a
relatively large time-step to be applied.
Implicit methods can be shown to be
numerically stable for large time-steps,
although it should be remembered that
selection of a large time-step may fail to
capture some higher-frequency (or shortertime duration) components of dynamic
• In implicit nonlinear analysis,
nonlinearities must occur within a timestep, and this, along with the frequent
solution of potentially large systems
of equations, adds complexity and
computational expense to implicit methods.
[ 24 ] MSC.Software
of relatively small time-steps. This makes
them much more suitable to short-duration
or highly dynamic applications such as
explosive loading, or those where the
material effects themselves are timedependent (strain-rate dependency). The
most common explicit schemes use the
‘central-difference’ approach and should
always be performed in conjunction with
a time-stepping algorithm that keeps below
the critical stability limit.
Due to potentially large relative deformations
and the capture of nonlinear material effects,
it is common for nonlinear FE simulations
to require more refined finite element meshes
than for linear analysis. Finite elements are
also known to lose accuracy when the original
mesh becomes highly distorted. Modern FE
codes account for this by providing
functionality (either manual or automatic)
to reconstruct or to rezone the mesh as the
nonlinear solution progresses. The ability to
improve the element shapes throughout the
analysis is critical in large-deformation
applications such as metal forming. α
To order MSC.Software’s Introductory
Guide to Nonlinear Analysis, log on to
www.mscsoftware.com/emea/nonlinear.
Complicated boundary conditions or other
forms of nonlinearity are also handled
easily since nonlinearities are handled after
a step has been taken. However, explicit
dynamics solution methods are inherently
unstable and rapidly diverge from a
meaningful solution unless the time-step
applied is both relatively small and shorter
than a calculated critical maximum value.
This means that explicit analyses are
generally characterised by a large number
5/19/05
11:01 AM
Page 3
Europe, Middle East, Africa | Munich, Germany – October 24-26
Japan | Tokyo, November 7-8
Americas | Spring 2006
Additional dates in AsiaPacific to be announced
Enhance innovation
Reduce product development risk and cost
Gain competitive advantage
Shorten time-to-market
Leverage engineering collaboration
If these are the goals set for your product
development efforts, attend one of
MSC.Software’s 2005 Virtual Product
Development (VPD) Conferences. The only
industry events dedicated to exploring all
aspects of VPD, the conferences bring together
engineering teams from the broadest range
“...an excellent mix of
senior management and
technical users...”
of industries to share the strategies and
technologies they are using to enhance concept
development, design, simulation, testing,
manufacturing, and business performance.
Last year, 90% of conference attendees rated
the event ‘very good to excellent,’ and more
than 95% said they would recommend
attending to their colleagues.
“Excellent conference –
good technical content,
great value.”
Featuring keynote speakers from leading
manufacturing companies, technical and
management presentations, specialized
seminars, workshops, exhibit areas, networking
opportunities, and more, our VPD Conferences
will give you the information, insight, and
inspiration you need to achieve your product
development goals.
For up-to-date conference details, registration information,
and highlights of past conferences, visit
http://vpd2005.mscsoftware.com
5/19/05
11:01 AM
Page 4
simulating
REALITY
TM
How did we cut our
time-to-market by 50%
and achieve significant
cost savings?
We used Virtual Product Development solutions
...from MSC.Software.
Global competition, economic challenges, and an accelerated race to market are
causing manufacturers to find new ways to reduce development time and cost. Virtual
Product Development (VPD) from MSC.Software makes this possible. Our market-leading
SimOffice tools such as MSC.Nastran, MSC.ADAMS, MSC.Marc, MSC.EASY5,
MSC.Patran, and more, empower your engineering team to design, test, and improve
the complete functional performance of your products faster and more economically
than ever before. And, our flexible, token-based MSC.MasterKey license system gives
you access to the tools you need, when you need them.
Discover how you can reduce product development time and cost – visit
vpdsuccess.mscsoftware.com or call us today at 1.800.397.6413.

Case Study - MSC Software Corporation

Transcription

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