Spatial Domain Modal Analysis of Lightly-Damped Structures Using Laser Velocimeters

Abstract

Traditional modal identification techniques do not take advantage of the high spatial density of scanning Laser Doppler Velocimeter (LDV) measurements. In this paper, a spatial modal parameter estimation technique, specially adapted for use with LDV measurements, is presented. It is based on a real-mode modal filtering concept and, therefore, is applicable to structures with low damping. From the estimated mode shape surfaces, curve-fitted with two-dimensional Fourier series, angular displacements are calculated. A rectangular plate example illustrates the proposed techniques with both numerically simulated and experimental results.