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Proceedings Paper

Dynamic characteristics and vibration-based damage inspection of structures with actual fatigue cracks
Author(s): P. Frank Pai; Jun Liu; Mannur J. Sundaresan
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Paper Abstract

This paper presents dynamic characteristics and damage inspection of beams with actual fatigue cracks by using a boundary-effect evaluation method (BEEM) to perform space-wavenumber analysis of operational deflection shapes (ODSs) and a conjugate-pair decomposition (CPD) method to perform time-frequency analysis of dynamic responses of some points to a harmonic excitation. 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. 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 methods for local spectral analysis based on local, adaptive curve fitting. Numerical simulations and experimental results show that dynamic characteristics of beams with actual fatigue cracks are different from those of beams with open artificial cracks. Moreover, 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 with actual cracks.

Paper Details

Date Published: 17 April 2013
PDF: 21 pages
Proc. SPIE 8695, Health Monitoring of Structural and Biological Systems 2013, 869533 (17 April 2013); doi: 10.1117/12.2009722
Show Author Affiliations
P. Frank Pai, Univ. of Missouri-Columbia (United States)
Jun Liu, Northwestern Polytechnical Univ. (China)
Mannur J. Sundaresan, North Carolina A&T State Univ. (United States)

Published in SPIE Proceedings Vol. 8695:
Health Monitoring of Structural and Biological Systems 2013
Tribikram Kundu, Editor(s)

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