A simplification and optimization approach for vehicle crashworthiness analysis: application on the NCAP MPDB crash test

Abstract

in the field of crashworthiness design, exploiting the full potential of weight reduction techniques while preserving the high safety standards of a vehicle still remains one of the major challenges. The computational cost of FEM simulations required to analyze the various crash load cases represents a real limitation to the optimization of vehicle structures. This aspect gets more relevant in load cases that include additional complex impactor models such as deformable barriers. To keep up with the ever-shorter stages of the Product Development Process (PDP), full vehicle crash models cannot be used directly for crashworthiness optimization. Similarly, conventional optimization approaches (e.g. based on Monte Carlo methods) cannot be applied successfully either. Therefore, there is a strong need for an automatic generation of simplified vehicle crash models. The main goal is the reduction of computational time while keeping the deviation of the simulation results as small as possible. This also enables structural optimization by means of suitable approaches that can operate with a minimal number of solver calls. In this work, an automated four-step approach to generate a simplified vehicle model and a simplification approach for deformable barriers are presented. Applying these approaches for the US NCAP front load case (100%, 56 km/h) with a validated Toyota Yaris model revealed that the number of components in the model could be reduced by 50%, and the computational time can be reduced by up to 90%. To show a suitable optimization approach with simplified FEM models, the Urban Modular Vehicle (UMV) designed by the German Aerospace Center (DLR) is investigated within the NCAP Mobile Progressive Deformable Barrier (MPDB) crash load case. A design optimization strategy based on mathematical surrogate models is successfully applied to optimize the absorption properties of the relevant structural components under specific safety constraints. As a final result, the Specific Energy Absorption (SEA) is more than doubled.