EVALUATION OF ADDITIVELY MANUFACTURED METALLIC MICRO-LATTICE FOR ENERGY ABSORPTION APPLICATIONS UNDER QUASI-STATIC AND DYNAMIC LOADINGS

Abstract

Truss lattice materials are man-made open porous cellular solids with periodic truss microstructures. Recent developments in additive manufacturing (AM) have enabled the fabrication of metallic lattice structures with dimensions close to micrometer scale. Among different lattice geometries, the octet truss lattice configuration is investigated in this study, as it provides nearly isotropic elastic properties and high specific strength. An extensive finite element (FE) parametric study was conducted on the design variables of the octet truss lattice aiming at increasing the specific energy absorption (SEA) and the energy absorption efficiency (EAE). Microlattice samples made from stainless steel 316L were manufactured using selective laser melting (SLM) based on the best design conditions obtained through the FE simulations. Quasi-static compression experiments were carried out on the fabricated samples which confirmed the results anticipated by FE simulations. In addition, the dynamic compressive behavior of the microlattice samples was reported from Split Hopkinson Pressure Bar (SHPB) testing technique at strain rate of the order 103/s. Additional experimental studies were performed to elaborate the effect of heat treatment and acrylic filling of the microlattice spaces on the microlattice large deformation behavior statically and dynamically.