ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2aSP6. A wavelet method for estimating frequency-dependent damping in structures.

Gary R. Wilson

Appl. Res. Labs., Univ. of Texas, P.O. Box 8029, Austin, TX 78713-8029

Estimation of damping from the measurement of the vibrations or acoustic radiation of structures provides some insight into energy storage and dissipation mechanisms in the structure. Because damping is typically proportional to frequency, a method of estimating damping that scales with frequency is suggested. A wavelet approach has been taken to exploit the natural scaling properties of wavelets to estimate frequency-dependent damping. A wavelet transform, the damped complex exponential (DCE) transform, has been designed specifically for measuring damping [R. D. Priebe and G. R. Wilson, IEEE ICASSP 3, 205--208 (1994)]. This transform has been applied to stimulate impulse response frequencies to determine its accuracy and sensitivity to mismatch between the assumed damping/frequency ratio used by the wavelet transform and the actual damping/frequency ratio of the impulse response. It has also been applied to the measured impulse response of a fluid loaded thin elastic shell. Results of these measurements show reasonable agreement with theoretical predictions of damping.