A SPACE-FREQUENCY DATA-COMPRESSION METHOD FOR SPATIALLY DENSE LASER-DOPPLER VIBROMETER MEASUREMENTS

When spatially dense mobility shapes are measured with scanning laser. Doppler vibrometers, it is often impractical to use phase-separation modal parameter estimation methods dire to the excessive number, of hi ghly coupled modes and to the prohibitive computational cost of proces sing huge amounts of data. To deal with this problem, a data compressi on method using Chebychev polynomial approximation in the frequency do main and two-dimensional discrete Fourier series approximation in the spatial domain, is proposcd in this article. The proposed space-freque ncy regressive approach was implemented and verified using a numerical simulation of a free-free-free-free suspended rectangular aluminum pl ate. To make the simulation more realistic, the mobility shapes were s ynthesized by modal superposition using mode shapes obtained experimen tally with a scanning laser Doppler vibrometer. A reduced and smoothed model, which takes advantage of the sinusoidal spatial pattern of str uctural mobility shapes and the polynomial frequency-domain pattern of the mobility shapes, is obtained. From the reduced model, smoothed cu rves with any desired frequency and spatial resolution can he produced whenever necessary. The procedure can be used either to generate nonm odal models or to compress the measured data prior to modal parameter estraction. (C) 1996 John Wiley & Sons, Inc.