Novel three-dimensional double-arrow negative Poisson's ratio metamaterials: experimental tests and numerical simulations

Negative Poisson's ratio (NPR) metamaterials exhibit exceptional mechanical properties, including the auxetic effect and high energy absorption, making them highly promising for applications in aerospace, automotive, marine, and other fields. Among these, the double-arrowhead (DAH) structure is a typical NPR metamaterial that has garnered significant research attention. However, conventional DAH structures often lack sufficient energy absorption capacity and compressive stability for engineering applications. To address these limitations, this study proposes a novel three-dimensional double-arrowhead metamaterial (NDAH) with improved compressive stability and energy absorption properties.Finite element models of the DAH and NDAH structures with equivalent relative densities were established, and their accuracy was validated through quasi-static compression tests. The experimental and numerical results demonstrate that the NDAH structure outperforms the DAH structure in terms of mechanical properties. Specifically, the specific energy absorption is increased by 55.39%, and the crushing force efficiency is increased by 63.8%,The mechanical properties of NDAH structure were compared with those of three-dimensional hexagonal double arrow structure at the same relative density to verify the advantages of NDAH structure in energy absorption.Furthermore, the effects of various geometric parameters on the deformation mechanism, Poisson's ratio, and energy absorption of the NDAH structure were analyzed. The findings reveal that parameters such as the short skew angle and width significantly influence the mechanical performance of the NDAH structure. Specifically, a smaller short skew angle, larger long skew angle, and a single-cell width-tothickness ratio of 1:2 effectively enhance compressive stability and energy absorption. These insights offer a novel approach to the structural design and mechanical properties of double-arrowhead metamaterials.