A novel 3D polygonal double-negative mechanical metamaterial with negative stiffness and negative Poisson’s ratio

Abstract

Materials with negative stiffness (NS) and materials with negative Poisson’s ratio (NPR) are two fundamental classes of mechanical metamaterials. The previous researches of double-negative metamaterials with simultaneous negative stiffness and negative Poisson’s ratio are either limited to two dimensions or challenging to realize experimentally. Here, a three-dimensional polygonal double-negative (PDN) metamaterial is proposed, which is formed by the auxetic framework and NS dome contact pairs. The main principle is that auxetic behavior is realized by sliding mechanism, whereby the sliding parts convert the applied vertical load into the horizontal compression load of the NS dome units, thus generating the negative stiffness characteristics. The double-negative metamaterial with quadrilateral profile shape (QDN) is studied by theoretical analysis and FEA simulation, and the response of the inversed-stacked QDN structure is verified by experiments. Furthermore, double-negative metamaterials with quadrilateral, hexagonal and cylindrical profile shapes are presented and their displacement conversion efficiency and Poisson’s ratio are analyzed and compared. The 3D polygonal double-negative structure can be applied to energy absorption due to its frictional action and elastic large deformation.