Time-frequency and space-wavenumber analysis for damage inspection of thin-walled structures

P. Frank Pai; Mannur J. Sundaresan

doi:10.1117/12.880329

18 April 2011 Time-frequency and space-wavenumber analysis for damage inspection of thin-walled structures

P. Frank Pai, Mannur J. Sundaresan

Proceedings Volume 7984, Health Monitoring of Structural and Biological Systems 2011; 79842J (2011) https://doi.org/10.1117/12.880329
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2011, San Diego, California, United States

Abstract

This paper presents a dynamics-based methodology for accurate damage inspection of thin-walled structures by combining a boundary-effect evaluation method (BEEM) for space-wavenumber analysis of measured operational deflection shapes (ODSs) and a conjugate-pair decomposition (CPD) method for time-frequency analysis of time traces of measured points. BEEM is for locating and estimating small structural damage by processing ODSs measured by a full-field measurement system (e.g., a scanning laser vibrometer or a camera-based motion measurement system). BEEM is a nondestructive spatial-domain method based on area-by-area processing of ODSs and it works without using any structural model or historical data for comparison. Similar to the short-time Fourier transform and wavelet transform, CPD uses adaptive windowed regular harmonics and function orthogonality to perform time-frequency analysis of time traces by extracting time-localized regular and/or distorted harmonics. Both BEEM and CPD are local spectral analysis based on local, adaptive curve fitting. The first estimation of the wavenumber for BEEM and the frequency for CPD is obtained by using a four-point Teager-Kaiser algorithm based on the use of finite difference. Numerical simulations and experimental results show that the combination of BEEM and CPD for space-wavenumber and time-frequency analysis provides an accurate tool for damage inspection of thin-walled structures.

Citation Download Citation

P. Frank Pai and Mannur J. Sundaresan "Time-frequency and space-wavenumber analysis for damage inspection of thin-walled structures", Proc. SPIE 7984, Health Monitoring of Structural and Biological Systems 2011, 79842J (18 April 2011); https://doi.org/10.1117/12.880329

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