Compressive performance and energy absorption of additively manufactured metallic hybrid lattice structures

A hybrid lattice cell configuration composed of an octet cell and a rhombic dodecahedron (RD) cell was proposed, aiming to combine the advantages of the bending-dominated and stretching-dominated structures. In order to examine the mechanical performance and energy absorption of the hybrid lattice, quasi-static compression experiments were conducted on the selective laser melting (SLM) printed samples made from 316 L stainless steel. The global deformation evolutions of the hybrid lattices were captured by a digital camera. Meanwhile, numerical simulations were carried out based on the cell assembly finite element (FE) models to reveal the localized deformation modes of the specimens tested in the experiments. Subsequently, parametric analysis was conducted according to the validated FE results to discuss how the overall relative density and volume fraction of each sub-cells influence the mechanical properties of the hybrid lattice structures. According to the experimental and numerical results, the hybrid structure exhibits smoother post-yielding response than the octet lattice and higher initial strength than the RD lattice, which contributes to its superior energy absorption capacity. The present study also demonstrates that the energy absorption abilities of the hybrid lattice structures can be further improved without sacrificing its load bearing capacity by tuning their mesoscopic architectures such as the ratio of each individual component. The experimental results also indicate that the hybrid design can be adopted to enhance the resistance of the lattice material to the process-induced geometric imperfections.