Effective mechanical properties of a two-dimensional tetrachiral metamaterial

Abstract

The paper is devoted to the study of mechanical properties of a two-dimensional tetrachiral mechanical metamaterial. To study the influence of the unit cell parameters of a metamaterial on its effective mechanical properties, we simulated the mechanical response of different metamaterial samples, in which the geometric parameters of the chiral unit cell were varied independently of each other. The mechanical behavior was studied under uniaxial compression of the sample. The simulation was carried out numerically using the finite element method. The influence of varied parameters on the transverse displacement of the moving end of the sample, caused by the «uniaxial compression-torsion» effect, and the effective elastic properties of a two-dimensional metamaterial were investigated. The greatest deformation, assessed by the deviation of the metamaterial sample from the initial position, is observed at commensurate sizes of the ring and ligaments. The correlation of the studied effective properties, as well as their connection with the «uniaxial loading-torsion» effect, is analyzed. The ability to resist uniaxial compression increases significantly, when adjacent cells touch and the twisting of tetrachiral structures is hindered. When the structure implements the twisting mechanism, the property of auxeticity manifests itself. The smallest effective Poisson's ratio was -0.1. This property disappears when the tetrachiral geometry of the metamaterial is violated.