Auxetic meta-materials and their engineering applications: a review

Abstract

Auxetic or negative Poisson’s ratio (NPR) materials and structures are exemplary mechanical meta-materials, possessing greater energy absorption capacity, stronger indentation resistance, and other advantages. Due to their unique indentation resistance, auxetic meta-materials have tremendous potential for use in impact engineering applications. To unveil the categories, characteristics, and applications of auxetic meta-materials, this study expounded upon the basic principles of auxeticity at the structural level and its associated mechanical properties. Additionally, it outlined the typical applications within the fields of medicine, automotive manufacturing, protective gear, and garments. The auxetic honeycomb structures of interest were first classified into three types: re-entrant, chiral, and rotational rigid structures. The auxetic mechanism and mechanical properties of these structures were then discussed and compared. Furthermore, by examining their current applications and characteristics of these structures, development directions for auxetic meta-materials were highlighted to meet future engineering demands for multi-functionality.