A novel auxetic 3D lattice structure for enhancing energy absorption

The auxetic lattice structures usually have excellent energy absorption characteristics since their failed part can resist crushing loads continuously. However, their platform stress is relatively lower and shorter than some conventional energy-absorbing lattice structures. A novel kind of auxetic three-dimensional (3D) lattice structure is proposed to overcome their shortcoming and improve energy absorption capacity. The proposed lattice structure is named as re-entrant-TPMS hexagonal (RTH), which consists of triply periodic minimal surface (TPMS) and 3D truss-based re-entrant hexagonal (RH) structures. The finite element (FE) method is employed to analyze the crashworthiness and Poisson’s ratio of RTH lattice structures, and the accuracy of the FE models is validated by comparing the existing experimental and theoretical results of the two sub-structures, respectively. The effect of various structural parameters on the energy absorption and negative Poisson’s ratio (NPR) effect of the RTH lattice structure is investigated to select the structure with better mechanical performance. The mechanism studies confirm that the platform stress is higher and longer compared to the 3D RH lattice structure. The NPR effect is also essentially consistent and accompanied by a stable shrinkage deformation due to the synergistic effect among the sub-structures. The proposed RTH lattice structure has potential applications in the crashworthiness design of carrier equipment for resisting more complex impact loads.