Underwater sound absorption and insulation of elastic micro-perforated plates in impedance tubes

Abstract

In this study, the underwater sound absorption and insulation performance capabilities of elastic micro-perforated plates (MPPs) in circular impedance tubes are investigated. The underwater sound absorption coefficient and the sound transmission loss (STL) of elastic MPPs are calculated by considering interaction between water and vibration of the elastic MPPs. As the frequency increases, higher order terms in addition to the plane wave solution are needed for convergence of the prediction. A comparison of the predictions from this study and the results obtained from the finite element method (FEM) shows good agreement. The fluid–structure interaction significantly affects the vibration of the MPP and the sound absorption characteristics are dominated by the vibration of the MPP, which results in sharp peaks in the sound absorption coefficient. For a low-frequency range, the characteristics of the STL are examined using a plane wave solution. The STL in water shows peaks, while that in air exhibits a wide bandwidth. For both underwater sound absorption and sound insulation, the peak frequencies remain nearly unchanged for different values of the cavity depth, and as the micro-perforation ratio increases, the peak frequencies increase.