Mechanical properties and band gap generation mechanism of a novel negative Poisson's ratio chiral metamaterial structure

Chiral metamaterials have been adopted in engineering fields due to their light weight, vibration isolation and load-bearing. In order to realize better impact performance and achieve the goal of low frequency and wide band gap, a new chiral sandwich metamaterial structure is proposed based on the macro/microscopic deformation mechanism of negative Poisson ratio material and energy absorption design. Based on Bloch Theorem, the theoretical model and the mechanism of band gap generation is revealed by analyzing the vibration mode at the boundary of band gap. The propagation characteristics of elastic waves are discussed by using three-dimensional dispersion surface, frequency contour, phase velocity and wave propagation direction. The mechanical properties and vibration transmission loss of the new metamaterial structure are numerically calculated and compared with the 3D-printed structure test. It is found that the novel metamaterial structure can generate multiple low-bandwidth band gaps, and the band gap can be flexibly adjusted according to the microscopic deformation and structural characteristics.