Elastically anisotropic architected metamaterials with enhanced energy absorption

Abstract

Materials and structures featuring a combination of high stiffness, strength, and energy absorption are highly demanded. Current studies are focused on the improvement of these mechanical properties without considering their directional dependence. In practice, directional-dependent mechanical properties are crucial to structural integrity and performance, for instance, in the application of anisotropic bone scaffolds for load bearing and battery separators for ion conductivity. Recently, tunable anisotropic stiffness in mechanical metamaterials has been obtained by tailoring the microstructures using data-driven approaches. However, energy absorption behavior, which plays a critical role in the presence of large deformation, has largely been neglected. In this work, we propose a new type of elastically anisotropic architected metamaterials (AAMs) inspired by the current lithium-ion battery separator porous microstructure to acquire tunable anisotropy while exhibiting superior energy absorption. The integrated study presented herein, which combines an experimental investigation with numerical simulations, reveals that the anisotropy can be engineered across a broad range. Compared with two existing lattice and shell-based architected materials, it is shown that the energy absorption of the newly developed AAMs is increased by 120% and 13%. The findings in this work provide a new strategy to expand the existing metamaterial design space, with the potential to enable innovative solutions for applications where directional-dependent stiffness and energy absorption are needed.