Response mechanisms and energy absorption properties of hybrid sheet TPMS lattices under static and dynamic loading

Triple Periodic Minimal Surface (TPMS) is widely used in many fields as a porous structure with light weight and high energy absorption efficiency. Based on uniform sheet TPMS lattices, a Gyroid-IWP Hybrid (GIH) sheet TPMS lattice was designed by internal cylindrical Gyroid lattice and external cubic IWP lattice. Specimens were fabricated by selective laser melting (SLM) technique and subjected to quasi-static compression and direct-impact Hopkinson bar (DIHB) experiments. The experimental results show that the hybrid GIH lattices exhibit more significant strain-hardening effects and higher energy absorption capacities than the uniform Gyroid and IWP lattices. And the GIH-I lattice (the lattice is compressed along the axis of the cylindrical Gyroid region) exhibits a relatively uniform deformation pattern. While the localized collapse of the GIH-II lattice (the lattice is compressed perpendicular to the axis of the cylindrical Gyroid region) firstly occurs in the IWP region at the two ends of the lattice, and then symmetrically collapses and deforms towards the intermediate transition layer. Finite element simulation was used to investigate the inner deformation mechanisms and energy absorption characteristics during the deformation processes. The effects of normalized hybrid diameters of the internal Gyroid region and the width of transition layer on the mechanical properties of the GIH lattice are also investigated. The results indicated that the GIH-I lattice has better impact resistance at low and medium strain rates, while the GIH-II lattice exhibits superior mechanical properties at higher strain rates. The GIH-II lattice not only has the smallest initial peak stress, but also exhibits significant multi-stage platform energy absorption. In addition, compared with the Linear Gyroid-IWP Hybrid (LGIH) lattices, the GIH lattices designed in this paper have obvious advantages under dynamic impact loading, which can provide a better design idea for engineering applications.