In-plane mechanical properties of a novel hybrid auxetic structure

Abstract

This paper presents a novel hybrid auxetic structure with enhanced mechanical properties, combining the re-entrant and double-arrowhead structures, based on the structural stretching-dominated deformation mechanism. The unit cell of the developed hybrid structure comprises an external quadrilateral frame and an internal arrowhead part. The theoretical analysis model for predicting its in-plane mechanical properties in the two principal directions is presented and verified by both numerical simulations and experimental measurements. On this basis, a parametric study on the in-plane mechanical properties of the hybrid structure is performed to optimize geometrical parameters. The results show that both the negative Poisson's ratio behavior and the elastic properties of the hybrid structure can be enhanced by increasing the length of the vertical wall or reducing the angle of the inclined wall in the internal arrowhead part. The hybrid structure, with the obvious difference in elastic properties between the two principle directions, can be obtained by individually adjusting the width of the hybrid unit cell, while the elastic properties in bothdirections can be improved by simultaneously reducing the length of the vertical wall and the width of the hybrid unit cell. In addition, compared with the re-entrant and double-arrowhead structures, the hybrid structure demonstrates higher elastic moduli and a wider range of Poisson's ratios from negative to positive. The study provides guidance for the optimized design of hybrid auxetic structures in practical applications.