Document Type thesis Author Name Shinde, Abhijeet Dipak Email Address abhijeet_wpi at yahoo.com URN etd-0824104-222824 Title A Wavelet Packet Based Sifting Process and Its Application for Structural Health Monitoring Degree MS Department Mechanical Engineering Advisors Prof. Zhikun Hou, Advisor Prof. Mikhail Dimentberg, Committee Member Prof. Michael Demetriou, Committee Member Prof. John Hall, Committee Member Prof. John Sullivan, Graduate Committee Rep Keywords Wooden Structure Damage Detection Structural Health Monitoring Instantaneous Modal Parameters Wavelet Analysis Time Varying Systems Sifting Process Date of Presentation/Defense 2004-08-19 Availability unrestricted
In this work an innovative wavelet packet based sifting process for signal decomposition has been developed and its application for health monitoring of time-varying structures is presented. With the proposed sifting process, a signal can be decomposed into its mono-frequency components by examining the energy content in the wavelet packet components of a signal, and imposing certain decomposition criteria. The method is illustrated for simulation data of a linear three degree-of-freedom spring-mass-damper system and the results are compared with those obtained using the empirical mode decomposition (EMD) method. Both methods provide good approximations, as compared with the exact solution for modal responses from a conventional modal analysis. Incorporated with the classical Hilbert transform, the proposed sifting process may be effectively used for structural health monitoring by monitoring instantaneous modal parameters of the structure for both, cases of abrupt structural stiffness loss and progressive stiffness degradation. The effectiveness of this method for practical application is evaluated by applying the methodology for experimental data and the results obtained matched with the field observations. The proposed methodology has shown better results in a comparison study which is done to evaluate performance of the proposed approach with other available SHM techniques, namely EMD technique and Continuous Wavelet Transform (CWT) method, for cases characterized by different damage scenarios and noise conditions.
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