Design and structural optimization of an assembled re-entrant auxetic structure

Abstract Auxetics represent a class of metamaterials that possess the unique quality of exhibiting a negative Poisson ratio. Considering the fact that the cross-section is reduced during compressive loadings, this class of materials and structures exhibit superior energy absorption capabilities in impact loadings, as the density of the material increases near the contact region. In this study, a novel approach in obtaining re-entrant auxetic structures is presented, consisting of the assembly and joining of components with simple geometries, that can be manufactured through conventional means (as opposed to additive manufacturing). The dimensions and aspect ratios of the structural members was evaluated numerically in order to obtain the optimal stiffness and strength values for a given mass. The design aspect also included special features that allows the assembly through shape, which facilitates the subsequent joining operation (welding or brazing).