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A wave-based damage
index for the analysis of the filtered response of damaged
beams
Nicole Apetre, Massimo Ruzzene, Sathyanaraya Hanagud and S. Gopalakrishnan |
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Vol. 3 (2008), No. 9, 1605–1623
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Abstract |
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This paper introduces a wave propagation-based damage index which relies on the evaluation of the strain energy distribution associated with propagating waves. The presence of localized damages typically distorts the wavefield by causing reflections and diffractions. The evaluation of such distortions, in reference to the wavefield corresponding to the undamaged structure, can be used as an indicator which potentially locates, quantifies and classifies the damage. The damage index formulation is first illustrated through a numerical model of a beam with a small notch, modeled as a localized thickness reduction. The beam’s wave propagation response is simulated through the combined application of perturbation techniques and the spectral finite element method. The perturbation approach and a first order model for the beam capture the coupling between bending and axial behavior caused by the damage, and allow the prediction of mode conversion phenomena. The perturbation solution allows direct comparison between undamaged and damaged strain energy contributions, which are directly associated with perturbation solutions of different orders. The resulting damage index locates the damage along the beam length and estimates its severity. Experimentally, the damage index is implemented by considering full wavefield measurements obtained through a scanning laser vibrometer. The undamaged reference response is derived directly from measurements on the damaged component, through the application of a filtering procedure operating in the wavenumber/frequency domain. |
Keywords
damage measure, damage index, notched beam, spectral finite
element method, perturbation techniques, first order beam
theory
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Milestones
Received: 19 December 2007
Accepted: 18 October 2008
Published: 1 November 2008
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Authors |
| Nicole Apetre | |
| School of Aerospace
Engineering Georgia Institute of Technology 270 Ferst Drive Atlanta, GA 30332 United States |
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| Massimo Ruzzene | |
| School of Aerospace
Engineering Georgia Institute of Technology 270 Ferst Drive Atlanta, GA 30332 United States |
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| http://www.ae.gatech.edu/people/mruzzene/ | |
| Sathyanaraya Hanagud | |
| School of Aerospace
Engineering Georgia Institute of Technology 270 Ferst Drive Atlanta, GA 30332 United States |
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| S. Gopalakrishnan | |
| Department of Aerospace
Engineering Indian Institute of Science Bangalore, 560012 India |
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| http://www.aero.iisc.ernet.in/~krishnan | |
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