A method for regulating negative Poisson's ratio by a reentrant anti-tetrachiral structure

Abstract

Auxetic structures with negative Poisson's ratio (NPR) have been drawing an increasing attention due to the distinctive mechanical performance, i.e. expanding laterally when stretched axially or contracting when compressed. And the mechanical characteristic can be tailorable, which has vast prospects in large deformation structures. In this study, a novel auxetic structure, named reentrant anti-tetrachiral (RATC) structure, is designed by introducing a reentrant angle into the existing anti-chiral structure. The present structure can exhibit a significant improvement of NPR. In order to facilitate numerical analysis, ABAQUS and Python script are utilized to generate numerical models with different configurations automatically. Then effects of geometrical parameters on the elastic modulus, shear modulus, Poisson's ratio and relative area (the ratio between base material area and unit cell area) are numerically investigated. The simulation results show that the structural parameters have great influence on the mechanical performance. Finally, additive manufacturing technique is employed to fabricate samples of the proposed design, which are subjected to uniaxial quasi-static tensile tests and three-point bending tests. The mechanical characteristics are verified through both simulation and experiments. Overall, the improved mechanical performance of RATC is demonstrated, which provides guidelines for auxetic structure designs.