Hyperbolic‐Like Structure with Negative Poisson's Ratio: Deformation Mechanism and Structural Design

Abstract

Mechanical metamaterials with negative Poisson's ratio (NPR) effect possess important practical applications in aerospace, nanotechnology, and other fields. The microstructure and its deformation mode directly determine the NPR ability and mechanical performance of auxetic metamaterials. Herein, inspired by the double‐negative‐index ceramic aerogels, a novel NPR structural model is proposed in which symmetric reentrant oblique ligaments and short transversal ligaments constitute the main framework inside a square, which is different from the traditional reentrant structure due to the hyperbolic‐like skeleton and deformation modes. The influence of structural parameters on the NPR effect is investigated using the Timoshenko beam model and finite element simulations. The structural model is then extended to design multiple reentrant structures and assembled structures, respectively. The multiple reentrant structures include multiple pairs of symmetrically hyperbolic‐like skeletons, and the distribution of horizontal ligaments can be regulated to achieve a better NPR effect. For assembled structures under compression, the local rotational deformation and buckling result in structural instability, demonstrated by inflection points in the NPR curves. Moreover, one special assembled structure is found for which there is a linear relationship between the compressive strain and NPR value. The insights should be significant for designing mechanical metamaterials with the NPR effect.