Crushing analysis and optimization for bio-inspired hierarchical 3D cellular structure

Three-dimensional (3D) cellular structures have been widely used in many aspects, e.g., protective equipment, aerospace, vehicles and so on, due to its lightweight and excellent energy absorption characteristics. Triply periodic minimal surface (TPMS) has more uniform energy absorption and mechanical properties than foam due to its structural characteristics. Therefore, a novel 3D hierarchical structure based on TPMS inspired by natural hierarchical biological structure is proposed in this study. Then, the numerical simulation is carried out using the nonlinear finite element code through LS-DYNA to study the crushing behavior of the hierarchical 3D cellular structure. And, the accuracy of finite element model is validated by quasi-static compression experiments on hierarchical structures manufactured by 3D printing. According to the numerical simulation results, the bio-inspired hierarchical 3D lattice is found to have excellent energy absorption characteristics than the non-hierarchical 3D lattice. In addition, the energy absorption characteristics of hierarchical structure is found to be affected by the design parameters of density and constant C. In order to obtain the optimal design of the bio-inspired hierarchical 3D lattice, Kriging (KRG) surrogate models and non-dominated sorting genetic algorithm II (NSGA-II) are jointly used to optimize the hierarchical 3D cellular structure. Moreover, the approximate expression of the specific energy absorption (SEA) of the hierarchical 3D cellular structure is obtained by fitting Gibson and Ashby empirical formula for prediction. Based on our study, the novel hierarchical 3D cellular structure has extremely excellent energy absorption characteristics and has very good application prospect in impact engineering.