Design optimization of a novel bio-inspired 3D porous structure for crashworthiness

Porous structure is widely used in automobile, aerospace and other industrial fields due to its lightweight and high energy absorption capacity. In this study, a novel porous structure, i.e. hierarchical three-dimensional porous (H3DP) structure inspired by the bone in nature is created based on the primitive triply periodic minimal surface sheet structure, which is a basic three-dimensional periodic porous structure consist of triply periodic minimal surfaces. The numerical simulation for the axial crushing of the H3DP structures is carried out using the nonlinear finite element code through LS-DYNA. For accuracy of the numerical results, the finite element model is validated by the experiment performed for H3DP structures which are manufactured by selective laser melting technology using a EOS M290 machine. The numerical results showed that this novel bio-inspired H3DP structure had excellent energy absorption capacity. However, the crashworthiness of the H3DP structure is affected by design parameters such as wall thickness, ribs thickness, number of inner ribs and distance between the inner and outer walls. In order to obtain the optimal design of the H3DP structure with the best crashworthiness, a multi-objective optimization is implemented employing the Kriging (KRG) surrogate modeling method and Non-Dominated Sorting Genetic Algorithm II (NSGA-II). According to the crashworthiness comparison of the H3DP structure and the traditional energy absorbed structures, it is found that the H3DP structure had relatively higher energy absorption capacity than the primitive sheet structure as well as lots of previous traditional materials or structures in nature and engineering. Thus, the H3DP structure can be used as a good energy absorbing structure and had good application prospect in the field of impact engineering.