A Novel 3D Chiral Metamaterial with Overall Compression-Twist Properties

Herein, 3D chiral compression-twist metamaterials represent a novel class of materials capable of converting compression into twist. An isotactic compression-twist lattice cell (ICTLC), composed of two identical chiral compression-twist units, is investigated in this paper. By compactly arranging ICTLCs, a 3D chiral metamaterial with overall compression-twist deformation is achieved. The mechanical properties and deformation mechanisms of the 3D chiral metamaterial are analyzed. The twist angle and the equivalent stress-strain relationship of the ICTLC are derived based on the deformation of its inclined rods under compression. An analytical solution for the twist angle of the 3D chiral metamaterial under in-plane compression is also presented. Both experiments and numerical simulations are conducted to verify the compression-twist performance of the proposed 3D chiral metamaterial. Additionally, the effects of the geometric parameters and the number of the ICTLC on the mechanical behavior and twist performance of the 3D chiral metamaterial are also investigated. The results indicate that, with a constant ratio of longitudinal ICTLC layers to transverse ICTLC rows (and columns), the compressive strength of the metamaterial increases while maintaining efficient compression-twisting deformation performance as the number of ICTLCs increases. These findings provide insights for the design of metamaterials with enhanced compression-twist coupling deformation.