315 / 2021-04-28 17:19:55

Bandgap mechanism and vibration attenuation of 1-D tetra-chiral metamaterials

Band gaps,Eigenstate mode,Vibration attenuation,Tetra-chiral metamaterials

Acoustic metamaterials and absorbing materials

Recently, the metamaterials with rotational/torsional resonators are proposed constantly to explore new vibration energy dissipation form. Inspired by the rotation property of chiral structures, the band gap mechanism and vibration attenuation characteristics of the 1-D tetra-chiral metamaterials are studied based on the discrete mass-spring model in this paper. The dispersion relation and band gaps of the mass-spring model are derived with lattice dynamics method. The effects of structural parameters, such as chiral angel, mass, stiffness and moment of inertia, on the bandgap generation are studied accordingly. Besides, the analytical solutions of band gap boundaries are obtained, which can provide prediction for band gap design. The eigenstate modes investigation reveals that the corresponding relationships between vibration modes and dispersion curves, and explains the generation mechanism of band gaps. The wave propagation characteristics of the system composed of finite unit cells show great agreement with the band gaps predicted by dispersion relation. Meanwhile, the energy components of motion in the finite cell units greatly illustrate that the resonators take away the vibration energy of main structure. Finally, the wave packet propagation along only three units attached system verifies the vibration attenuation characteristics of the proposed 1-D tetra-chiral acoustic metamaterials effectively.