Reconstructing non-stationary surface normal velocity of a planar structure using pressure-velocity probes

Abstract

An acoustic method based on the time domain plane wave superposition method is proposed to reconstruct the non-stationary surface normal velocity of an impacted planar structure by measuring the normal particle velocity. In this method, the time-evolving normal particle velocity on the hologram plane is first measured by pressure-velocity probes; then, the normal particle velocity spectrum on a virtual source plane is used to establish the relationship between the time-evolving normal particle velocity on the hologram plane and the time-evolving surface normal velocity on the structural plane; finally, the normal particle velocity spectrums can be solved by an iterative solving process and are used to calculate the non-stationary surface normal velocity of the planar structure. An experiment of a planar steel plate impacted by a steel ball is presented to examine the ability of the proposed method, where the time-evolving normal particle velocity and pressure on the hologram plane measured by pressure-velocity probes are used as the inputs of the proposed method and the pressure-based reconstruction method, respectively, and a laser Doppler vibrometry is used to measure the surface normal velocity of the plate as the reference for comparisons. The comparison results demonstrate that the proposed method is effective in reconstructing the non-stationary surface normal velocity in both time and space domains and can provide more accurate results than that of the pressure-based reconstruction method.