Modal analysis of a circular disc using the QLPdecomposition of FRF matrices

Abstract

"A circular disc is used to demonstrate the application of the pivoted QLP decomposition to the analysis of the frequency response data for a structure possessing double modes. Frequency Response Functions (FRFs) are generated for excitation and response points on the disc rim. Plots of L-values and Q-response functions obtained by the QLP decomposition with column pivoting are used to determine the system order, damped natural frequencies and modal damping ratios, as well as mode shapes. The performance of the LMIF, QMIF and QCoMIF mode indicator functions is assessed in the presence of degenerate modes. Enhanced FRFs based on QRFs are used with single degree of freedom parameter identification techniques. "