Bandgap properties in metamaterial sandwich plate with periodically embedded plate-type resonators

In this study, a novel plate-type resonator is proposed, and the bandgap properties of a metamaterial sandwich plate containing a two-dimensional periodic array of these plate-type resonators are numerically and experimentally investigated. The finite element method is applied to calculate the band structure and the transmission spectra. The formation mechanisms of the bandgaps are investigated via the analysis of the mode shapes of the plate-type resonator and face plate in a unit cell. The results demonstrate that both locally resonant and Bragg bandgaps exist in the proposed structure. The selective coupling between the resonant modes of the plate-type resonator and the face plate is a necessary condition for the generation of locally resonant bandgaps that the resonant modes of the plate-type resonator can produce a reaction force on the support. The effect of the geometric parameters and surface mass ratio on the bandgaps is investigated, and the effect of the introduction of the plate-type resonator on the Bragg bandgap is studied. The improvements of the plate-type resonator by changing its structure or moving its attachment point are also discussed. Moreover, a metamaterial sandwich plate specimen is fabricated and vibration experiments are conducted, and it is observed that there is good agreement between the numerical predictions and the experimental results. The proposed strategy contributes to the possibility of fabricating a simpler structure to promote the exploitation of metamaterial sandwich plates in engineering. (C) 2020 Elsevier Ltd. All rights reserved.