The Near-field's Acoustic Properties Of An Elastic Plate

As a new kind of underwater acoustic measurement equipment, the vector hydrophone is widely apply to underwater sound domains such as the submarine signal detection and target identification. When the vector hydrophone used in various submarine platform, the scattering of sound by the platform influences the vector hydrophone's working conditions seriously. In order to expand the vector hydrophone's applicable scope, various acoustic parameters of near-field in the elastic thin steel plate are investigated.The major work carried out are:(1)The Rayleigh wave, the Stoneley wave and the Love wave were qualitative analyzed through wave equation and boundary conditions, and then the paper focused on the Lamb wave dispersion curves which excited by a low-frequency wave.(2)Based on the modeling of an infinite elastic thin steel plate which immerged in the water, the plate's vibration impedance was analyzed, the results shows that the flexural vibrations which was excitated by a low-frequency wave was impossible to inspire the inhomogeneous wave. And when the thin plate free vibrates, the propagation characteristics of sound in the surrounding fluid were investigated. The paper also discussed the propagation characteristics of sound in the surrounding fluid when the thin plate excited by plane wave.(3)The paper calculated the reflection coefficient of an infinite thin elastic steel plate which immerged in the water through the theory of elasticity, and gave a farther study about near-field's acoustic response functions, then had carried on the corresponding simulation using Matlab.(4)Various acoustic parameters spatial distribution of the near-field and the scattering field in the finite elastic plate have been obtained by the numerical technique (FEM+BEM), and a further analysis about the relations between the angle of incident sound source and the acoustic parameters such as pressure, particle velocity and sound intensity is investigated at a certain distance which is from the geometric center of thin plate(5)In order to verify the theory of the infinite elastic plate, a corresponding experiment in the noise elimination pool is carried on. Good agreement is achieved between the experimental result the theoretical value.