Isotropic hybrid architected foams with enhanced energy absorption

Abstract

Automotive and defense industries have been calling for the lightweight materials and structures with excellent energy absorption property under extreme operating conditions. Toward this end, random foams, and architected materials with different building blocks (beam, plate, and shell) have been investigated. However, most of the studied metamaterials exhibit anisotropic mechanical behavior upon different loading conditions. In practice, engineering materials are mostly expected to display isotropic mechanical properties at the macroscopic level. Random foams have been reported the first-generation man-made porous isotropic metamaterials, but they are characterized by the stochastic, uncontrollable topologies and material distributions which make them inferior candidates by contrast to architected metamaterials. In this work, we conducted systematically numerical experiment on a novel design of hybrid SC-BCC foam structure, which exhibits nearly isotropic mechanical behavior with nearly linear scaling relationship between relative stiffness and relative density. Remarkably, the proposed hybrid foam shows significantly improved stiffness, yield strength, and energy absorption compared to SC-foam. The stiffness and strength of hybrid foam are increased by 237% and 177% compared to SC-foam. The energy absorption of hybrid foam is increased by 96.5% and 28.1% compared to SC-foam and BCC-foam, respectively. The findings in our work offer new insights to design isotropic architected materials with enhanced mechanical performance that can find applications ranging from structural components of defense systems to protection systems in vehicles.