TY - GEN

T1 - Modal identification from nonstationary ambient vibration data using random decrement algorithm

AU - Lin, Chang Sheng

AU - Chiang, Dar-Yun

PY - 2012/7/24

Y1 - 2012/7/24

N2 - An effective identification method is developed for the determination of modal parameters of a structure from its measured ambient nonstationary vibration data. It has been shown in a previous paper of the authors that by assuming the ambient excitation to be nonstationary white noise in the form of a product model, the nonstationary response signals can be converted into free-vibration data via the correlation technique. In the present paper, if the ambient excitation can be modeled as a nonstationary white noise in the form of a product model, then the nonstationary cross random decrement signatures of structural response evaluated at any fixed time instant are shown theoretically to be proportional to the nonstationary cross-correlation functions. The practical problem of insufficient data samples available for evaluating nonstationary random decrement signatures can be approximately resolved by first extracting the amplitude-modulating function from the response and then transforming the nonstationary responses into stationary ones. Modal-parameter identification can then be performed using the Ibrahim time-domain technique, which is effective at identifying closely spaced modes. Numerical simulations confirm the validity of the proposed method for identification of modal parameters from nonstationary ambient response data.

AB - An effective identification method is developed for the determination of modal parameters of a structure from its measured ambient nonstationary vibration data. It has been shown in a previous paper of the authors that by assuming the ambient excitation to be nonstationary white noise in the form of a product model, the nonstationary response signals can be converted into free-vibration data via the correlation technique. In the present paper, if the ambient excitation can be modeled as a nonstationary white noise in the form of a product model, then the nonstationary cross random decrement signatures of structural response evaluated at any fixed time instant are shown theoretically to be proportional to the nonstationary cross-correlation functions. The practical problem of insufficient data samples available for evaluating nonstationary random decrement signatures can be approximately resolved by first extracting the amplitude-modulating function from the response and then transforming the nonstationary responses into stationary ones. Modal-parameter identification can then be performed using the Ibrahim time-domain technique, which is effective at identifying closely spaced modes. Numerical simulations confirm the validity of the proposed method for identification of modal parameters from nonstationary ambient response data.

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U2 - 10.1007/978-1-4614-2425-3_20

DO - 10.1007/978-1-4614-2425-3_20

M3 - Conference contribution

AN - SCOPUS:84864000930

SN - 9781461424246

T3 - Conference Proceedings of the Society for Experimental Mechanics Series

SP - 223

EP - 232

BT - Topics in Modal Analysis I - Proceedings of the 30th IMAC, A Conference on Structural Dynamics, 2012

T2 - 30th IMAC, A Conference on Structural Dynamics, 2012

Y2 - 30 January 2012 through 2 February 2012

ER -