FREQUENCY-DOMAIN MODAL PARAMETER-IDENTIFICATION OF HIGH-ORDER SYSTEMSIN A NUMERICALLY STABLE WAY

Frequency domain modal parameter identification methods have several a ttractive properties as compared with the time domain methods except f or the limitation of low-order-and-narrow-band per analysis. As rule o f thumb, a limit of less than ten modes has been observed for several popular frequency domain algorithms. However, this paper will show, th at with a proper and thorough use of the orthogonal polynomials in the frequency domain, the number of modes per analysis can be increased t o as high as 75 in a comparatively wide frequency range of interest wh ile still retaining numerical stability. Both numerical example (75 mo des in 5-1000 Hz) and experimental data analysis (56 modes in 50-5000 Hz) are presented to demonstrate the effectiveness of this innovative approach.