Experimental and numerical investigation on effects of viscoelastic rubber and local resonator mass on broadband vibration attenuation in acoustic-metamaterial plates

Vibration attenuation in acoustic-metamaterial plates assembled from a periodic arrangement of unit cells with a cavity containing local resonator system is presented. Each cell incorporates a base aluminum plate with vertical rectangle-shaped cavities containing a viscoelastic membrane supporting a mass forming a local resonator system. These acoustic-metamaterial structures exhibit stop-band behavior due to Bragg scattering and local resonance. Floquet–Bloch approach and eigenvalue analysis is used to identify the stop bands for metamaterial unit cells. The dispersion analysis predictions are validated experimentally by studying the vibration responses of different acoustic-metamaterial plates excited by an electrodynamic shaker over a frequency range of 8−4000 Hz. The attenuation regions observed in the finite element simulation results have been compared to that of the experiments. The obtained results show the potential of FE simulation to predict the metamaterial plate attenuation with reasonably good accuracy. The viscoelastic material properties also affect the attenuation region, as observed while comparing experimental results for different viscoelastic materials. These results show the effectiveness of acoustic-metamaterial plates to provide broadband vibration attenuation.