applications


to detect the start of a failure and its propagation through a material.’ Di Valentin gave an example of a project to


optimise the development of a B-pillar, which is a vertical pillar connecting the roof and the base of a car: ‘For this component, we have 15,000,000 elements to simulate rupture.’ Di Valentin explained that the project was particularly useful as it gave an opportunity for Altair to test the capability of RADIOSS on large-scale HPC systems, while also improving PSA’s knowledge on the propagation of material failure. Te project was run on the Curie


supercomputer, owned by GENCI and operated by Te French Alternative Energies and Atomic Energy Commission (Commissariat à l’énergie atomique et aux énergies alternatives) or CEA. Jean Michelle Terrier, Altair vice president


of RADIOSS business and research and development stated that access to the CEA supercomputer was provided through the Partnership for Advanced Computing in Europe (PRACE). Te model describing rupture used in this


project was created through the ‘Industrial Fracture Consortium,’ which included members from MIT, Ecole Polytechnique and industrial partners like PSA.


WORKING WITH THESE


RELATIVELY NEW MATERIALS REQUIRES OEMS TO INVESTIGATE NEW MATERIAL LAWS


‘Today cars are quite complex,’ commented


Terrier. ‘You have a lot of lightweight materials such as aluminium, magnesium, composites and plastics – and you also have high strength steel, which has a very specific behaviour.’ Terrier explained that working with these


relatively new materials requires OEMs to investigate new material laws that can correctly model the behaviour of plastics, or of composites, for example. Tese studies help soſtware providers and commercial companies to develop numerical tools and design rules that can support the use of new materials – accurately predicting material failures. Te aim of the Altair/PSA project was to


improve their ability to assess predictive rupture models, and to identify a viable solution for testing ruptures on a massive scale. First, Altair engineers ported RADIOSS to


Bullxmpi for the Curie supercomputer. Ten, two specific models were developed to study rupture of a B-pillar component, with mesh size requirement of 75µm element length.


www.scientific-computing.com l Simulation of a crash using Deltagen Real Impact Visualisation. @scwmagazine OCTOBER/NOVEMBER 2016 31 Te first model – created by Altair, with 15


million of elements – was used to assess scalability of the code up to 8,192 cores. A second model was built by PSA, with mesh optimisation reducing element number to 10 million.


Employing optimisation in crash simulation Tese tools are used not only by commercial vehicle manufacturers but also in academia as Jingwen Hu, an associate research scientist at the University of Michigan Transportation Research Institute Biosciences Group explains. Hu stated that he had been using simulation for around 18 years, but first discovered Esteco through a seminar at Wayne State University, where he was pursuing his master’s degree in engineering. Hu stated that, approximately 10 years ago, he


saw a seminar at the university about optimising crash simulation using modeFrontier. Hu explained that he had been using the soſtware since that time because of its ease of use, and of the work that Esteco put into providing support for its users. Esteco’s modeFrontier soſtware is designed to


facilitate multidisciplinary optimisation. Tis can be particularly useful in crash simulation, as it allows hundreds or thousands of variations of a model to be simulated – automating the process of optimising the design based on pre-selected parameters Jingwen Hu explained that some of his recent


research has focused on the optimisation of seatbelt restraints using Estceco’s modeFrontier soſtware. He discussed two projects to improve crash safety; the first focused on the seatbelt interlock, a US requirement that prevents engine ignition if the front seatbelt is not fastened. Tis study looked at the benefits of removing


this feature for belted and unbelted occupants. Te second project investigated crash safety in the rear of the vehicle; the study focused on the protection afforded by seat restraint systems on a


diverse population of passengers, from adults to infants in a booster seat. For this study, the researchers created models


of response surface methods (RSM) to optimise the variables of the restraint system, allowing them to simulate thousands of potential variations. Te results show that removing the interlock system would allow automotive manufacturers to optimise seat restraints for belted occupants (around 86 per cent of drivers in the US) better. ‘Tis regulation decreases the protection of


people that wear the seatbelt’ continued Hu. ‘If we removed this regulation, then people who wear the seatbelt would have better protection. But, you might not have an overall benefit of injury reduction because, as you improve the protection for the belted occupants, you decrease protection for the unbelted occupants. Te second study focused on the optimisation


of seat restraints in the rear of a car based on a diverse population of occupants. Hu explained: ‘For the people who do sit in the rear seat we have a very diverse population. In the front seat typically, it is adults, but in the rear seats we have a lot of kids, including those that will sit in the booster seat.’ Tose children in booster seats are oſten


well protected by the position of the booster seat, which is optimised around small children. However, children in the range of six- to 12-year- olds oſten cannot use seatbelts correctly, so this study was aimed at optimising seat restraints for these occupants. ‘Tis study looks at whether we can change the


rear seat stiffness, cushion length and the seatbelt anchorage locations to protect older children better,’ commented Hu. Tis study demonstrates that there is no


single solution for all rear seat occupants, as each population is optimised in different ways. ‘Older kids will be better protected by a shorter seat cushion, while infants in the car seat will ➤


Dassault Systemes /Honda


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