Superior compressive performance of hierarchical origami-corrugation metallic sandwich structures based on selective laser melting

Novel hierarchical origami-corrugation metallic sandwich (HOCM) structures have been proposed, by replacing the facets of the Miura-Ori patterned foldcore with smaller-scale corrugated sandwiches. A series of as-fabricated and after-heated samples were additively manufactured from two high-strength metals (i.e., IN718 and 17-4PH) by selective laser melting (SLM) technique. The microstructure of HOCM samples, and the post-fracture of parent materials were characterized. Quasi-static out-of-plane compressive behavior of the HOCM structures was experimentally and numerically investigated, with an excellent agreement between the measurements and FE simulations. Effects of relative density and parent material (especially the heat treatment) on the compressive properties were explored in terms of deformation mechanism, compressive strength and energy absorption. The layer-by-layer small-scale folding deformation dominating in the crushing process contributes to a relatively high and long stress-plateau stage, which leads to the excellent energy absorption. The heat treatment of the HOCM samples increases the compressive strength, but might not benefit the energy absorption. The IN718 and 17-4PH hierarchical origami-corrugation metallic sandwiches exhibit very competitive mechanical properties compared to cellular topologies, and possess great potential as lightweight load-bearing and energy-absorbent engineering components.