Design and Characterization of New 3D Reentrant Rhombic Auxetic Structures with Enhanced Mechanical Properties

In this study, a new reentrant rhombic auxetic structure is first designed by replacing the reentrant strut of the regular reentrant structure with a rhombic structure. A simulation calculation method verified by experimental results is comprehensively developed to reveal the compressive behavior of the proposed structures in terms of deformation pattern, compression strength, Poisson's ratio, and energy absorption (EA). Based on the validated simulation method, the results indicate that compression load can give rise to an “X” deformation pattern of the rhombic auxetic structures. In the structure parametric study, it is further proved that the unit configuration exhibits a significant influence on the compression stress and EA of the structures. Furthermore, the rhombic auxetic structures present diverse Poisson's ratios with the structure parameters and compression global strain, that is, the structures with larger H, smaller D, and θ are found to present more pronounced auxetic effect. The compression direction also exhibits a remarkable effect on the performance of the structure, which accordingly indicates the anisotropic characteristic of the proposed structures. Moreover, compared with the other regular auxetic structures, the rhombic auxetic structures exhibit superior mechanical behavior and EA feature due to the introduction of the rhombic structure.