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International Conference on Structural Engineering Dynamics – ICEDyn 2009
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Detection of Nonlinearity in a Dynamic System Using Deformation Modes Obtained from the Wavelet Transform of Measured Responses
Nguyen Viet Ha
,1 Peeters Maxime,1 and Golinval Jean-Claude11University of Liege, Aerospace and Mechanical Engineering Department, Structural Dynamics Research Group, Chemin des Chevreuils 1, B52, B-4000 Liege, Belgium
Abstract
An efficient approach to Structural Health Monitoring of dynamical systems based on the Wavelet Transform (WT) and the concept of subspace angle is presented. The objective is to propose a detection method that is sensitive to the onset of nonlinear behaviour in a dynamic system. For this purpose, instantaneous frequencies are identified first from output-only vibration signals using the Wavelet Transform. Time varying deformation shapes are then extracted by analyzing the whole measurement data set on the structure. From this information, different dynamic states of the structure may be detected by inspecting time variations of 'modal' features. The experimental structure considered here as application example is a clamped beam with a geometric nonlinearity. Detection of nonlinearity is carried out by means of the concept of subspace angles between instantaneous deformation modes extracted from measurement data using the continuous Wavelet Transform. The method consists in controlling the angular coherence between active subspaces of the current and reference states respectively. The proposed technique, which shows a good sensitivity to small changes in the dynamic behaviour of the structure, may also be used for damage detection.
Copyright
Copyright © 2010 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
