Todd L. Harbold
Courtney B. Burroughs
Appl. Res. Lab., Penn State Univ., P.O. Box 30, State College, PA 16801
The spatial distribution of the amplitude and phase of the velocity of vibrating rectangular flat plates is measured using a scanning laser Doppler vibrometer. These measurements are conducted in a nonanechoic environment with the plate in air and water, driven by a single shaker at frequencies of resonance and nonresonance. Using free-field Green's functions and fast Fourier transform (FFT) algorithms, the free-field acoustic radiated field for the unbaffled plate is determined. In order to compute the acoustic radiation, the velocity field must be specified in the plane of the plate, both on and off the surface of the plate. Therefore, an iterative process is used to determine the velocity field off of the plate surface. Descriptions of the plate vibration measurements and algorithms used to compute the free-field acoustic radiated field are presented and discussed. Examples of results of measurements conducted at and off resonance are given.