Rainbow zigzag metamaterial beams as broadband vibration isolators for beam-like structures

Abstract

Unlike conventional metamaterials with a periodic array of identical resonators, rainbow metamaterials consist of an array of discrete resonators with a spatially varying parameter, yielding a wide attenuation band gap. In this research, a particular kind of gradient zigzag metamaterial beam with rainbow effects is proposed with the gradual height change of Π -shaped unit cells in the metamaterial beams. The calculated real and complex band structures using the finite element method (FEM) and the spectral element method (SEM) show the very different characteristics of our gradient zigzag metamaterial beams. Their band structures are exclusively composed of flat bands caused by the local resonance of certain parts in the gradient zigzag metamaterial beams within a broad frequency range. As a result, our proposed gradient zigzag metamaterial beams can be used as broadband vibration isolators for beam-like structures, supported by both the numerical simulations and experiments conducted on the 3D-printed samples. In addition, our gradient zigzag metamaterial beams allow for wave reciprocity, and the disorder of unit cell heights has a negative effect on the widening of the attenuation band gap. This design strategy opens a new avenue for designing and constructing novel broadband vibration isolators.