19th Asia-Pacific Vibration Conference (APVC2021)

428 / 2022-08-01 18:41:09

Calibrating Acoustic Field of a Vibrating Structure Located near a Pressure-Release Boundary

Near-field acoustical holography,half-space spherical wave functions,pressure-release boundary

This paper develops a method based on near-field acoustical holography for calibrating the acoustic field radiated directly from a vibrating structure located in a half space bounded by a pressure-release boundary.  First, the series of half-space spherical wave basis functions satisfying the pressure-release boundary condition is formulated. Then the acoustic field in the half space is modeled using an expansion in this basis. The expansion coefficients are determined by solving an overdetermined linear system of equations, obtained by matching this expansion to the measured half-space acoustic pressures. The pressures radiated directly from the source can finally be reconstructed using the free-space spherical wave function expansion with the obtained expansion coefficients.  Numerical simulation examples of a vibrating plate located in water near a pressure-release boundary are demonstrated to validate the proposed method. The effects of various parameters, such as the acoustic frequency, the distance between the source and boundary, and the orientation of the source surface, on the reconstruction accuracy are examined.