MOVING TOWARDS ZERO-PROTOTYPING

FOR AUTOMOTIVE PASSIVE SAFETY

 Challenge:
• Automakers today face unprecedented
pressures to meet and exceed ever-changing
crashworthiness standards while responding
to consumer demands, higher gas mileage Think global, but simulate local as well
requirements and complex, new materials. How Accurate prediction of crashworthiness depends
they respond to these challenges directly impacts on simulation of all phenomena that might affect the
their bottom line. performance of a vehicle in a crash event. This includes
global distortions of the car body and chassis, as well
Solution: as ‘local’ failure mechanisms of materials such as the
• Working closely with SIMULIA over almost a sheet metal and internal joining techniques such as spot
decade, BMW Group’s R&D team developed a welds and adhesives. Developing and deploying accurate
simulation program, based on Abaqus FEA, that simulation capabilities for these local failure mechanisms
moved them towards a stated corporate goal of has been a key factor in BMW Group’s zero-prototype
zero-prototyping for passive safety. achievement.

Benefits: The graph shows the difference in simulation results for

• Such a simulation-driven strategy yields the firewall intrusion into the passenger compartment for
significant savings in both costs and product an offset frontal crash test, comparing the earlier (green
line) modeling technique and the newer (red line) modeling
development time. The engineering team now
technique.
has a comprehensive view of component and
full-car behavior during crash scenarios and The virtual vehicle model without local failure mechanisms
confidence in the accuracy of their simulations. predicted an intrusion of the firewall that was 30% stiffer
The launch of the BMW 6 Series Gran Coupé than the more complete model that included all important
failure mechanisms. In other words, the less complete
marks the first car platform for which zero-
model led to the non-conservative prediction that there was
prototyping was accomplished for passive safety.
less intrusion into the passenger compartment than would
actually occur. The newer, more comprehensive approach is
employed as standard practice in all crash simulations.

Automobile safety standards have become a moving target for

manufacturers. As current and future requirements become
increasingly stringent, automakers must perpetually stay a
step ahead, designing and building accordingly. As a result, the
latest car models are the safest ever and highway fatality rates
are at an all-time low.
While meeting—and even exceeding—safety requirements
is clearly a priority for automakers, the drive to improve 0,000 0,040 0,080 0,120 0,160

vehicle safety is just one of several factors creating economic Without Material and
pressures on OEMs these days. Customer demands for a wider Spotweld Failure
With Material and
variety of car models and performance characteristics, tougher Spotweld Failure

mileage standards that require reduced vehicle weight, and

the development of more advanced materials—all these need
to be factored into vehicle design without compromising
crashworthiness. Staying cost-competitive under these
conditions, while continuing to attract enthusiastic customers,
is an ongoing priority for carmakers.
Frontal offset crash test simulation in Abaqus FEA (top) and
One tool that is increasingly proving its worth—from R&D corresponding firewall intrusion results with and without
department to factory floor to crash-test hall to auto showroom— local failure mechanisms incorporated in the model (bottom).
is simulation software. Early adopters have grown their
in-house design engineering expertise alongside advancements
in computer modeling technology with extremely positive
prove out and leverage the predictive worth of simulation to
results.
the point where prototypes could be eliminated for the passive
Thought leaders across the automotive industry recognized safety design of a car model.
years ago that the multiple challenges of vehicle development,
underscored by the need to meet ever-updating safety The limits of physical prototyping
standards, could only be addressed successfully with improved While simulation has been employed in passive safety design
design simulation to help identify the most creative, robust, for many years, physical prototypes are still commonly built
cost-effective route to success. An ambitious longer term goal: and tested during the course of a vehicle development program.
These pre-production vehicles are expensive and time-intensive for that load case. This level of predictiveness would be key to
to build and crash test, due in large part to the soft prototype enabling truly virtual design iterations where important design
tooling and hand fabrication required. decisions are made based on realistic simulation results.
This type of hardware proofing has other limitations, all of Throughout the virtualization partnership, SIMULIA experts
which either constrain or influence results: it’s impossible to worked closely with BMW Group engineers to implement and
test for all load cases in this way, and test results are not fully test new capabilities in Abaqus, often in response to specific
transferable to cars that roll off the production line since these requirements from the automaker. New features were validated
prototype vehicles are hand-assembled approximations of through increasingly close correlation between simulation
series production vehicles. results and real-world test data.

An ambitious goal: reduce prototyping The BMW 6 Series Gran Coupé was then chosen as the first
through simulation BMW Group car model where a zero prototype approach to
vehicle development would be undertaken.
Premium automaker BMW Group and Dassault Systèmes
SIMULIA, provider of the Abaqus FEA software suite, have Moving directly from design to hard tooling
partnered for more than ten years in passive safety design
A number of virtual passive safety design iterations were carried
simulation in pursuit of this product development evolution.
out during the BMW 6 Series Gran Coupé development utilizing
For computer-aided design (CAD), the automaker uses CATIA
the accumulated simulation results to make subsequent design
V5 (also from Dassault Systèmes).
modifications. The final design was predicted to meet all
While earlier simulations had accurately demonstrated global passive safety performance targets.
vehicle behavior during a collision, the team recognized that
Confidence in this final design eliminated the usual soft tooling
detailed local behaviors of materials and connections that could
stage for prototyping, so that BMW Group could proceed
lead to damage and failure needed to be considered as well (see
directly to series production with hardened production tooling.
sidebar below). For instance, it would be critical to accurately
Physical crash test results from these early series production
simulate the potential localized damage to the sheet metal
vehicles closely matched the simulation predictions and the
and spot welds in the B-pillar for a side crash test, in order to
BMW 6 Series Gran Coupé was launched.
accurately predict the passive safety performance of the vehicle

B-pillar

hydraulically
operated impactor

V=2mm/s
(quasi-static loading)

Simulation Experiment
Simulation (Abaqus)
70000
Test 1
Test 2
60000

50000

40000
Force [N]

30000

20000

10000

0
0 50 100 150 200 250 300 350 400 450 500
Simulation Experiment Displacement [mm]

Figure 1. Abaqus simulations of material failure behavior in B-pillar deployment in production design simulation. Leveraging realistic
intrusion experiment. The test is deliberately carried out to complete simulation to achieve such accurate local predictions within global design
failure, and so the corresponding forces are higher than typically occur in models early in the vehicle program increases vehicle design
a crash event. Predicted crack initiation and propagation correlated development efficiency by avoiding problems later, when changes are
highly with test data, validating the material modeling approach for more costly to correct and can impact vehicle launch timelines.
 The journey continues
The high level of predictiveness of the simulations gives
engineers greater insight into how to improve and optimize
future car designs. As vehicle platforms continue to evolve—to
multi-material construction—simulation will be an instrumental
tool for designers and engineers. SIMULIA will continue to
collaborate closely with BMW Group to ensure that passive
safety simulation capabilities in Abaqus are enhanced to
accommodate fresh platforms and ever-more stringent safety
requirements.
Figure 2. Modeling potential sheet metal failure during a crash test
simulation is standard practice at BMW Group. The figure on the left Of course real-world crash tests are always the final proof for
shows the typical body components where this is considered. The assessing the ultimate value of simulation. While creating and

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effects of prior forming processes, such as stamping, can have an following a roadmap towards zero-prototyping takes time
influence on failure, and the figure on the right shows the typical

©2015 Dassault Systèmes. All rights reserved. 3DEXPERIENCE®, the Compass icon and the 3DS logo, CATIA, SOLIDWORKS, ENOVIA, DELMIA, SIMULIA, GEOVIA, EXALEAD, 3D VIA, 3DSWYM, BIOVIA, NETVIBES, and 3DXCITE are commercial trademarks
and commitment, accurate and robust simulation capabilities
components where results from earlier forming simulations are mapped
onto their crash model counterparts. can and should play a central role, enabling automakers to
reach new passive safety milestones throughout the product
development journey.

Figure 3. Side impact load cases are often the most difficult from a
crashworthiness perspective. The figures above show actual BMW 6
Series Gran Coupé results for two standard side crash tests: IIHS side
impact with moving deformable barrier (left); and FMVSS 214 side pole
impact (right). For each, the corresponding design simulation results are
also shown which accurately predicted the passive safety performance
and led to the zero-prototype success.

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