Design of gradient foam metal materials with a constant impact load

Abstract

Cellular materials can absorb a large amount of impact energy with large deformation, and their crashworthiness may be improved by introducing density gradients. The macroscopic mechanical responses of graded cellular materials are very sensitive to their relative density distributions and the effects of meso-structures can be very different. Some of existing studies is mainly limited to the analysis on the dynamic mechanical response of graded cellular material with a given density gradient, and less on the crashworthiness design method is considered. Based on the nonlinear plastic shock wave model, a backward crashworthiness design method is developed for graded foams. A simplified model and an asymptotic solution are derived by applying the series method with the aim of maintaining a constant load on the impact object. The cell-based finite element models based on three-dimensional Voronoi structures with density continuously changing are constructed by applying the variable cell size method. The theoretical design is verified by using finite element software ABAQUS/Explicit. The numerical simulation results show that the asymptotic solution of the simplified model is effective for the crashworthiness design of graded foams, and the proposed crashworthiness design method is of instructive significance in controlling the energy absorption and impact process.