Time-Frequency Domain Modal Parameter Estimation of Time-Varying Structures Using a Two-Step Least Square Estimator

Conference paper
Part of the Conference Proceedings of the Society for Experimental Mechanics Series book series (CPSEMS)


Under natural stochastic excitations, responses of time-varying structures are always nonstationary stochastic signals, of which spectra change with time. This paper studies the time-dependent power spectrum density based on time-frequency analysis. Based on the time-dependent power spectrum density, a mathematical model of the time-frequency-domain two-step least square modal parameter estimator for time-varying structures is presented. In the first-step estimation, the modal parameters at each time instant are estimated using the least square complex frequency-domain method. Furthermore, the estimated modal parameters are sifted and sorted. Based on the sifted and sorted modal parameters, the time-varying resonance frequency, damping ratio and operational mode shapes are estimated in the second-step estimation. A numerical simulation example and a group of experiments validate this two-step least square modal parameter estimator for time-varying structures.


Time-varying structure Time-frequency analysis Modal parameter estimation Two-step least square 



The authors acknowledge the support for the work presented in this paper from the China Scholarship Council and Katholieke Universiteit Leuven.


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Copyright information

© The Society for Experimental Mechanics, Inc. 2012 2012

Authors and Affiliations

  1. 1.School of Aerospace EngineeringBeijing Institute of TechnologyBeijingChina
  2. 2.Department of Mechanical EngineeringKatholieke Universiteit LeuvenLeuvenBelgium

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