Shock and Vibration

Shock and Vibration / 2010 / Article
Special Issue

International Conference on Structural Engineering Dynamics – ICEDyn 2009

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Open Access

Volume 17 |Article ID 492943 | 16 pages | https://doi.org/10.3233/SAV-2010-0543

Detection of Nonlinearity in a Dynamic System Using Deformation Modes Obtained from the Wavelet Transform of Measured Responses

Received18 Jun 2010
Accepted18 Jun 2010

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 © 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.

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