SMP-based anisotropic chiral metamaterials with tunable mechanical properties and band gap characteristics

Traditional chiral metamaterials have some shortcomings, such as no obvious anisotropy, narrow strain range and fixed mechanical properties, thereby limiting their applications. In this study, a novel SMP-based anisotropic chiral metamaterial with elliptic nodes was designed and manufactured to investigate its tensile deformation characteristics through experiments and simulations. Based on the reliable experimental and numerical results, a theoretical model was further established to obtain the force-strain and Poisson's ratio-strain response mechanisms of anisotropic chiral metamaterial with different node shapes, node angles and ligament thicknesses. It was confirmed that the introduction of elliptic node and SMP base material efficiently enhanced the structural anisotropy, lengthened the strain range and achieved a controllable adjustment of shapes and stiffness and function driven by temperature. The dispersion relationship and band gap of the anisotropic chiral metamaterial were also studied. The results show that the anisotropic chiral metamaterial had a complete and directional band gap, which prevented the propagation of elastic waves in a specific direction within certain frequency ranges. The design idea is expected to provide a good support for their potential applications in flexible constructions and vibration isolation.