Vibro-acoustic metamaterial for longitudinal vibration suppression in a low frequency range

This study proposes a theoretical model of a vibro-acoustic metamaterial for longitudinal vibration suppression in a low frequency range and computationally and experimentally demonstrates the vibration attenuation performance of the proposed metamaterial. The vibro-acoustic coupling analysis is performed on a theoretical model in which a discrete vibration system and a short-length duct are periodically repeated. The transfer matrix method and the Bloch-Floquet theorem were developed to calculate the Bloch phase of a unit cell of the proposed vibro-acoustic metamaterial. Its stop band predicted from the Bloch phase commenced at 0 Hz and coincided with the frequency range of low transmissibility (<1). The effects of unit cell parameters on the upper limit frequency of the stop band are discussed, and the dispersion relation and effective mass density curves of the proposed vibro-acoustic metamaterial explain its underlying physics. The developed theoretical approach is extended to vibro-acoustic metamaterials including a continuous vibration system, instead of a discrete vibration system, for actual application. Finite element analysis and experiments on the extended vibro-acoustic metamaterials were performed to validate the vibration attenuation performance of the proposed metamaterial, which can be used to suppress longitudinal vibration waves transmitted between two mechanical parts.