PAM-CRASH

PAM-CRASH is a software package from ESI Group used for crash simulation and the design of occupant safety systems, primarily in the automotive industry. PAM-CRASH enables automotive engineers to simulate the performance of a proposed vehicle design and evaluate the potential for injury to vehicle occupants in various crash scenarios. Automobile manufacturers typically simulate multiple alternative designs during the product development process in order to improve the crashworthiness of the vehicle.

History

PAM-CRASH originated in research aimed at simulating aerospace and nuclear applications. On May 30, 1978 ESI Group simulated the accidental crash of a military fighter plane into a nuclear power plant in a meeting organized by VDI (Verein Deutscher Ingenieure) in Stuttgart.^[1] German automobile manufacturers took note and tested the applicability of several emerging commercial crash simulation codes, including what would soon become PAM-CRASH. As part of this project, PAM-CRASH predecessor code simulated the frontal impact of a full passenger car structure in an overnight computer run. This was the first successful full-car crash simulation.^[2]

Based on Finite Element Method (FPM), PAM-CRASH enables the modeling of complex geometry by offering a large panel of structural and continuum elements: beams, shells, membranes and solids. In a typical vehicle crash simulation, shells are used to model thin-walled metal,plastic and composite components. Beams and bars may also be used for stiffening frames, suspensions and special connections. The program offers a large range of linear and nonlinear materials including elastic and visco-plastic and including foam materials and multi-layers composites up to damage and failure models.^[3]

PAM-CRASH was used in the first numerical simulation of a full vehicle rollover by BMW AG (Bayerische Motoren Werke AG). Finite element simulation provided accurate determination of the structural deformations while computationally economical rigid body simulation was used during the relatively unimportant deformation and free-flight phases of the simulation.^[4]

The software has been improved over the years. PAM-CRASH 2G, introduced in 2002, allows consideration of manufacturing effects during the design process by chaining the simulation of casting, stamping and composites forming processes to crash simulation.^[5]

PAM-CRASH has been successfully adapted for High Performance Computers use on massively parallel systems. One of the most time critical part of the parallel simulation is the contact handling. Results of measurements on a 128-processor machine demonstrated that a contact search algorithm leads to a better scalability.^[6]

Engineers utilize crash simulation not only to determine the end result of the crash but also to view the step by step time history. By viewing factors such as how the bumper is folded in the impact and what is the effect of rib thickness on body deformation in the initial stages of the simulation, engineers can often gain insights that help them improve the crashworthiness of the vehicle design.^[7]

Desktop Engineering magazine, in its review of ESI Group’s Virtual Performance Solution, which includes PAM-CRASH, said: “The Virtual Performance Solution embraces a lot of things, such as gold-standard tools like PAM-CRASH. But what it really provides you is an integrated simulation environment. That is what makes it so cool. And so does this: You work across multiple analysis domains with a single core model – not different models for every load case. This streamlines your workflow, saving time and money by reducing the number of individual solvers you have to deploy and all that model re-creation business.”^[8]

Applications

PAM-CRASH was used to design a floor pan structure to meet torsion and bending stiffness requirements of a steel automotive floor pan while reducing its weight by 50% and the number of parts by 70%. The crashworthiness of the composite floor pan design was evaluated by reproducing the same loading and support conditions of the Euro NCAP pole side impact crash test. The numerical results were then compared against the experimental data from two crash tests.^[9]

PAM-CRASH was dynamically coupled to the occupant safety program MADYMO. The technique combines the advantages of the finite element method for the solution of dynamic problems with large structural deformations with value of validated occupant models. The study investigated the interaction of a Hybrid III crash dummy and a passive restraint system consisting of an airbag and a kneebolster in a frontal impact situation. Good agreement with experimental data was obtained. However, due to the increased request on results accuracy and prediction, this is replaced by a full finite element simulation using FE dummy models. The increased computation resources needed were compensated by optimized architecture code and improved hardware performances.^[10]

Researchers at the University of North Carolina and Mississippi State University simulated various crash scenarios on a Chrysler Neon passenger vehicle using PAM-CRASH and another crash simulation code. The test data and simulation results correlated very well with only minor discrepancies in terms of overall impact deformation, component failure modes and velocity and acceleration at various locations on the vehicle.^[11]

PAM-CRASH was used to evaluate safety issues at the Beryl Bravo offshore platform in the North Sea which is operated by ExxonMobil. ExxonMobil made the decision to upgrade existing fire barriers adjacent to the process and compression areas into blast walls that would be capable of containing an explosion in these areas without rupture and would provide a fire barrier. PAM-CRASH was used to perform numerical simulations of the dynamic response of the structure subjected to explosion scenarios. The PAM-CRASH computation models agreed with experimental results and were used to guide the process of designing the new blast walls.^[12]

PAM-CRASH is used by automobile manufacturers to improve their rankings in New Car Assessment Programs (NCAPs) that are intended to provide consumers with a realistic and independent assessment of the safety performance of competing automobile models. These programs include the Euro NCAP and Japan NCAP as well as a similar rating system provided by the National Highway Traffic Safety Administration (NHTSA).^[13]

References

1. ^ E. Haug. (1981) "Engineering safety analysis via destructive numerical experiments", EUROMECH 121, Polish Academy of Sciences, Engineering Transactions 29(1), 39–49.
2. ^ E. Haug, T. Scharnhorst, P. Du Bois (1986) "FEM-Crash, Berechnung eines Fahrzeugfrontalaufpralls", VDI Berichte 613, 479–505.
3. ^ Eric Mestreau, Rainald Lohner. “Airbag Simulation Using Fluid/Structure Coupling.” 34th Aerospace Sciences Meeting & Exhibit, Reno, NV, January 15–18, 1996.
4. ^ A.K. Pickett, H.G. Hoeck, A. Poth and W. Sehrepfer, “Crashworthiness analysis of a full automotive rollover test using a mixed rigid body and explicit finite element approach.” VDI Berichte 816, p 167-179.
5. ^ Niizeki Hiroshi. “Second Generation Crash Analysis Software PAM-CRASH '2G' V2002.” Nihon Kikai Gakkai Nenji Taikai Koen Ronbunshu. 2002, Vol.5, Pages 199-200.
6. ^ Jan Clinckemaillie, Hans-Georg Galbas, Otto Kolp, Clemens August Thole and Stefanos Vlachoutsis. “High Scalability of Parallel PAM-CRASH with a New Contact Search Algorithm.” Lecture Notes in Computer Science. 2010 Volume 1823.
7. ^ L. Durrenberger, D. Even, A. Molinari1 and A. Rusinek. “Influence of the strain path on crash properties of a crash-box structure by experimental and numerical approaches.” J. Phys. IV France 134 (2006) 1287-1293.
8. ^ Anthony J. Lockwood, “Editor's Pick: ESI Releases Virtual Performance Solution 2010.” Desktop Engineering. July 2010.
9. ^ M. Carrera, J. Cuartero, A. Miravete, J. Jergeus, Kaj Fredin. “Crash behavior of a carbon fiber floor panel.” International Journal of Vehicle Design. Volume 44, Number 3-4 / 2007, Pages: 268 – 281.
10. ^ Rainer Hoffman, Dirk Ulrich, Jean-Baptiste Protard, Harald Wester, Norbert Jaehn, Thomas Scharnhorst. „Finite Element Analysis of Occupant Restraint System Interaction with PAM-CRASH.” 34th Stapp Car Crash Conference, Orlando, Florida, November 4–7, 1990.
11. ^ K. Solanki, D.L. Oglesby, C.L. Burton, H. Fang, M.F. Horstemeyer. “Crashworthiness Simulations Comparing Pam-Crash and LS-DYNA in CAE Methods for Vehicle Crashworthiness and Occupant Safety and Safety-Critical Systems.” Society of Automotive Engineers. 2004.
12. ^ P.H.L. Groenenboom, P.J. van der Weijde, D.N. Gailbraith, P. Jay. “Virtual Predictive Testing and Virtual Prototyping in Safety Engineering.” 5th International Conference on Offshore Structures – Hazards & Integrity Management, London 1996.
13. ^ Philipp Spethmann, Cornelius Herstatt, Stefan H. Thomke. “Crash simulation evolution and its impact on R&D in the automotive applications.” International Journal of Product Development. Volume 8, Number 3 / 2009.