Study of Mechanical Properties of a New 3D Re-Entrant Lattice Auxetic Structure Under Bending

Herein, the mechanical behaviors of a new 3D re-entrant lattice auxetic structure under bending are investigated. When a classical 3D re-entrant lattice auxetic structure is subjected to uniaxial loading, only one 2D structural component can sustain the load, which limits the capability of the auxetic structure. By changing the connection mode of 2D components, a new 3D re-entrant lattice auxetic structure that can exhibit both in- and out-of-plane negative Poisson's ratios is proposed. To investigate the bending response of the new structure, specimens with three different design parameters are additively manufactured, and their mechanical properties are studied with the four-point bending test and finite element analysis. Compared to the classical 3D re-entrant lattice structure, the new 3D re-entrant lattice structure exhibits lower initial peak stress and higher energy absorption capacity. The underlying mechanism may be closely associated with the unique deformation pattern of auxetic structures under bending. The new re-entrant auxetic structure expands the design space of 3D auxetic structures, especially for energy absorption and protection in impact scenarios.