Abstract
The identification of modal parameters from the response data only is studied for structural systems under nonstationary ambient vibration. In a previous paper by the authors, the modal parameters of a system were identified using the correlation method in conjunction with the curve-fitting technique. This was done by working within the assumption that the ambient excitation is a nonstationary white noise in the form of a product model. In the present paper, the Ibrahim time-domain method (ITD) is extended for modal-parameter identification from the nonstationary ambient response data without any additional treatment of converting the original data into the form of free vibration. The ambient responses corresponding to various nonstationary inputs can be approximately expressed as a sum of exponential functions. In effect, the ITD method can be used in conjunction with the channel-expansion technique to identify the major modes of a structural system. To distinguish the structural modes from the non-structural modes, the concept of mode -shape coherence and confidence factor is employed. Numerical simulations, including one example of using the practical excitation data, confirm the validity and robustness of the proposed method for identification of modal parameters from the nonstationary ambient response.
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This paper was recommended for publication in revised form by Associate Editor Ohseop Song
D. Y. Chiang received his Ph.D. in Applied Mechanics from the California Institute of Technology, USA in 1992. He joined the faculty of National Cheng Kung University, Taiwan in 1993 where he is currently a professor at the Department of Aeronautics and Astronautics. His research interests are system identification and plasticity.
C. S. Lin received his B.S. and M.S. degrees from the Department of Aeronautics and Astronautics of National Cheng Kung University, Taiwan in 2002 and 2004, respectively. He is currently a Ph.D. candidate with research interests in random vibration and modal analysis.
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Chiang, DY., Lin, CS. Identification of modal parameters from nonstationary ambient vibration data using the channel-expansion technique. J Mech Sci Technol 25, 1307 (2011). https://doi.org/10.1007/s12206-011-0229-y
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DOI: https://doi.org/10.1007/s12206-011-0229-y