Optimisation for bending crashworthiness of functionally graded foam-filled cellular structure

Due to extraordinary energy absorption capacity as well as light weight, functionally graded foam-filled cellular structure (FGFCS) has gained considerable attention. Using nonlinear finite element method through LS-DYNA, this work studied the bending crashworthiness of nine FGFCSs with different cross-sectional configurations. The results demonstrate that the bending crashworthiness of the FGFCSs is significantly affected by the design parameter of the graded functional parameter q. Thus, in order to find the optimal gradient exponential parameter, the FGFCSs with different cross sections were optimised using the radial basis function metamodel and the Non-dominated Sorting Genetic Algorithm II. Meanwhile, the corresponding uniform foam-filled cellular structures (UFCSs) with the same weight as above FGFCSs were also optimised in our study. In the optimisation process, the aim is to achieve maximum value of specific energy absorption and minimum value of peak crushing force. By comparing the Pareto fronts obtained by multi-objective optimisation, it can be found that FGFCSs have better crashworthiness than the corresponding UFCSs in most considered cases. Thus, the optimal design of FGFCS has exactly an excellent energy absorption capacity under lateral impact and can be used in the future vehicle body.