Compressive mechanical properties of a novel three-dimensional auxetic structure based on additive manufacturing

Auxetic metamaterials are a class of functional materials with negative Poisson's ratio (NPR) properties achieved by artificially designing internal auxetic structures, which have broad application prospects in aerospace, shipbuilding, and other fields due to their excellent impact resistance, high specific stiffness, and unique mechanical behaviors. In this work, we propose a novel three-dimensional (3D) lattice asymmetrical re-entrant triangular (ART) structure (LART) based on two-dimensional (2D) ART, and the samples were manufactured by the liquid-crystal display (LCD) 3D printing technology. The crushing response of LART under quasi-static compression and the effects of structural parameters on the mechanical properties were investigated by a combination of experiments and finite element (FE) simulations. The results show that LART has an obvious NPR performance and the mechanical properties of LART can be tunable by changing the parameters. Additionally, the effects of wall thickness and cell numbers on LART were also studied using FE simulations. Finally, the LART was compared to the 2D-ART and 3D re-entrant lattice structure (3D-RE) to highlight the design advantages. The results show that LART has superior load-bearing capacity than the other two structures and the values of specific energy absorption (SEA) are 17 and 2.34 times higher than those of 2D-ART and 3D-RE, respectively. None of the LART configurations researched in this paper showed unstable deformation with unilateral buckling, which demonstrates its potential application in fields such as soft robotics and electronic devices.