On the influence of frequency selectivity of wavelet bases for relative wavelet entropy-based structural damage localization

Gkoktsi, K. & Giaralis, A. (2014). On the influence of frequency selectivity of wavelet bases for relative wavelet entropy-based structural damage localization. Paper presented at the 6th World Conference on Structural Control and Monitoring, 15-07-2014 - 17-07-2014, Barcelona, Spain.

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Wavelet analysis of vibration signals measured by sensors placed on dynamically excited linear structures has proved to be an effective tool for detection and localization of structural damage. Recently, it has been shown that the relative wavelet entropy (RWE) computed from signal energy-preserving wavelet coefficients of vibration signals from “healthy” (reference) and from “damage” structural states is a potent tool for structural damage assessment applications. Herein, the influence of the frequency domain (FD) properties of the adopted analysis wavelet basis on the efficiency and robustness of the RWE for structural damage localization is assessed. To this aim, simulated benchmark free vibration signals from different locations of a simply supported beam “damaged” at various different positions are discrete wavelet transformed by three different analyzing wavelet bases: Daubechies wavelets (non-compactly supported in the FD), Meyer wavelets (compactly supported in the FD with overlapping frequency bands among wavelet scales), and harmonic wavelets (compactly supported in the FD with non-overlapping frequency bands among wavelet scales) are utilized. A wavelet scale dependent RWE-related index plotted against the frequency axis along the length of the beam is utilized to compare the effectiveness of the wavelet bases considered for damage position inference. The reported numerical data demonstrate that compactness in the FD and frequency selectivity among wavelet scales offered by Meyer and harmonic wavelet bases enhances the damage localization potential of the RWE compared to the commonly considered in the literature Daubechies wavelet bases. Furthermore, it is shown that non-constant Q analysis readily achieved with harmonic wavelets is advantageous over the standard discrete wavelet transform constant Q analysis, Q being the ratio of central frequency over bandwidth at each wavelet scale, to discriminate RWE contributions at high frequencies. It is concluded that judicial construction of wavelet analysis bases or, equivalently, of discrete wavelet analysis filter banks, in the FD is an important aspect for effective damage localization of linear vibrating structures based on the concept of the RWE.

Item Type: Conference or Workshop Item (Paper)
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Divisions: School of Engineering & Mathematical Sciences > Engineering
Related URLs:
URI: http://openaccess.city.ac.uk/id/eprint/3994

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