SMP-based chiral auxetic mechanical metamaterial with tunable bandgap function

Artificial designed metamaterials have attracted widespread attention because of its unique lattice structure and special physical properties. In this work, a chiral auxetic metamaterial with adjustable band gap function is designed based on the shape memory polymer (SMP) with special thermomechanical property. Theory and finite element methods are used to investigate the relationship between the elastic modulus, Poisson's ratio and lattice parameters of the chiral metamaterial. Moreover, the dispersion curves of the metamaterial under different strain states and temperature field are studied by finite element method. The evolution processes of the band gap with the variation of configuration and environmental temperature are systematically revealed. The results show that the elastic modulus can be tailored by adjusting the geometric parameters of the lattice, and the Poisson's ratio is -1. The band gap could be real-time adjusted by external stimuli (mechanical loadings, temperature field). Based on the relationship between the geometric parameters and the band gap, the required properties of metamaterial can be customized. Moreover, the vibration control ability of the metamaterial can be further optimized by adjusting the strain of metamaterial and the temperature. The method of designing metamaterials with tunable and programmable mechanical properties and acoustic functions provides a meaningful reference for the development of metamaterials with potential applications.