Effect of Amplification on Acoustic and Vibration Energy with Vibroacoustic Coupling

概要

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In order to apply acoustic energy to industrial fields, its amplification is essential and vibroacoustic coupling is one of best ways of amplifying acoustic energy. In the present study, we consider a cylindrical structure with thin plate at both ends and investigate vibroacousitc coupling between the plate vibrations and internal sound field when an external harmonic force is applied to one end plate, regarding such a coupling phenomena as one of the available measures to amplify acoustic energy. This coupling is theoretically and experimentally investigated by considering the behavior of both plates and the acoustic characteristics of the internal sound field for varying dimensions of the end plates and the cylinder. In the analytical model, the end plates are supported circumferentially by springs in order to obtain support conditions that are as close as possible to the actual condition in the experiment due to adjustments of spring stiffnesses. The cylinder length and phase difference, which maximized the sound pressure level inside the cavity, are clarified theoretically. These theoretically results are verified experimentally through an excitation experiment using an experimental apparatus that is emulated by the analytical model. The above-describe results reveal such a vibroacoustic coupling phenomenon is useful for the amplification of the acoustic energy.