Multiobjective optimization for foam-filled multi-cell thin-walled structures under lateral impact

• The crashworthiness of nine FMTSs under lateral loadings was first investigated.
• The COPRAS method was used to determine the ranks of crashworthiness of the FMTSs.
• A MMO method employing PR models and MOPSO was developed to optimize the FMTSs.

Nowadays, foam-filled multi-cell thin-walled structure (FMTS) has been widely used in the field of automotive due to their extraordinary energy absorption capacity and light weight. In this study, nine kinds of FMTSs with different cross-sectional configurations under lateral crushing load conditions were investigated using nonlinear finite element method through LS-DYNA. The complex proportional assessment (COPRAS) method was used to make clear which kind of FMTSs has the most excellent crashworthiness. According to this method, it can be found that FMTSs with 2, 3 and 9 cells are the top-3 excellent structures in our considered cases. In order to improve the crashworthiness of the three FMTSs, they were optimized by metamodel-based multiobjective optimization method which was developed by employing polynomial regression (PR) metamodel and multiobjective particle swarm optimization (MOPSO) algorithm. In the optimization process, we aimed to achieve maximum value of specific energy absorption (SEA) and minimum value of maximum impact force (MIF). Based on the comparison of the Pareto fronts obtained by multiobjective optimization, we can find that FMTS with 9 cells (FTMT9) performs better than FMTSs with 2 and 3 cells. Thus, the optimal design of FMTS9 is exactly an excellent energy absorption candidate under lateral impact and can be used in the future vehicle body.