Analysis of the low-frequency vibration attenuation capability of a novel thin-plate acoustic metamaterial

In this paper, based on the local resonance mechanism, four thin elastic plate structures with low-frequency bandgap are proposed through structural design and optimization. The first bandgap onset frequency of the optimized plate structure is lower than 100 Hz, which realizes low-frequency vibration damping and provides an effective method for subsequent low-frequency vibration damping research. It is analyzed that the bandgap is caused by the offset of the resonance form, and the opening of the low-frequency bandgap is due to the local resonance of the scatterer and the substrate, and the forms of the scatterer resonance include the offset resonance and the rotational resonance. Group velocity and phase velocity images show that frequency variations have a significant effect on energy transfer, wave speed and wave direction in the structure. The frequency response spectra obtained from vibration transfer experiments well verify the accuracy of the band gap. Displacement clouds of the finite period structure are cross-checked with the vibration modes of the modeled single cell. The minimum value of the transmission coefficient T of the proposed plate structure in the range of 0–300 Hz is −91.8, which corresponds to frequencies in the bandgap range with strong vibration attenuation. The bandgap characteristics vary with the material parameters with a clear regularity. These four structures have great potential for application in practical engineering involving low-frequency noise and vibration suppression.