Ultra-low density architectured metamaterial with superior mechanical properties and energy absorption capability

The material with negative Poisson's ratio (NPR) is a typical metamaterial, which is considered to have great prospects in energy absorption, but the low modulus and low strength of the materials are the biggest obstacles to its engineering applications. In this paper, the basic mechanical properties and energy absorption performance of an auxetic material with ultra-low density, named as a novel cross-chiral structure (NCCS), are systematically studied under quasi-static and dynamic compression. The results reveal that this auxetic material shows strong anisotropy and enhanced mechanical properties in the principal directions. Compared to the previously reported auxetic materials, it exhibits higher modulus and strength as well as superior energy absorption capability with the relative density less than 0.1, which is validated by both numerical simulations and experiments. In addition, the results indicate that the presented model can be optimized to achieve excellent mechanical properties and outstanding energy absorption capability with ultra-low densities, by tailoring strut's tilt angle and relative density. This architectured metamaterial is expected to find a bright future in the applications of energy absorption such as sandwich cores of armor.