Compressive mechanical properties of bidirectional gradient TPMS lattice structures

Compared with conventional lattice structures, triply periodic minimal surface (TPMS) lattice structures exhibit superior mechanical performance, and the gradient design is an effective way to further enhance their performance. To this end, four different TPMS lattices with bidirectional gradient (TPMS-BG) configurations are proposed by using self-coupling and cross-coupling of asymmetric and symmetric gradients. The compressive mechanical properties are systematically investigated using numerical simulations and experimental observations, which indicate that the mechanical properties of TPMS-BG structures are significantly superior to those of conventional uniform structures. Among various structures, the cross-coupled configuration with a symmetric gradient in the compression direction presents the optimal performance, while the cross-coupled structure with an asymmetric gradient exhibits the least favorable. The compressive mechanical properties of TPMS-BG structures are further enhanced with an increase in the gradient factor. Furthermore, the TPMS-BG configurations in the positive gradient direction provide superior energy absorption, while those in the negative gradient direction provide higher stiffness. The crashworthiness and lightweight performance of TPMS-BG structurres is also substantiated by the Gibson–Ashby model, which suggests that they present excellent crashworthiness potential and that their performance is enhanced as the relative density decreases.