Damage identification in beams using speckle shearography and an optimal spatial sampling

Mininni, Marco; Gabriele, Stefano; Lopes, H.; Santos, J.V. Araújo dos

doi:10.1016/j.ymssp.2016.02.039

Cited by 27 publications

(30 citation statements)

References 25 publications

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“…Further extension of that research lead to work by Mininni et al [20], which employed shearography to experimentally determine the location and the magnitude of damage using a dimensionless curvature damage factor. The method was successful in determining the location and magnitude of damage on several examples.…”

Section: Introductionmentioning

confidence: 99%

Local bending stiffness identification of beams using simultaneous Fourier-series fitting and shearography

Zastavnik

Pintelon

Kersemans

et al. 2019

Journal of Sound and Vibration

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In this paper, we present a novel method for the identification of the local bending stiffness of a beam. We use shearography to capture measurements of vibrating beams, so the input data for the identification is the modal slope-the differential of the modal shape. The modal slope is fitted by two Fourier-series functions, one of which is derived from a thin-beam model. The local bending stiffness is identified as the one corresponding with the best match between the measured and the two fitted modal slopes. This identification method, which we call simultaneous Fourier-series fitting, is demonstrated on numerically-generated inputs, as well as on experimental measurements. We use a flat, concave and convex beam, as well as beams with locally varying bending stiffness mimicking local damage to verify the method. It is shown that the method gives accurate results and is robust to noise. Additionally, it has advantageous properties that make it useful and practical: using this method, it is possible to perform the identification from only a sub-region of a beam and even without specifying the boundary conditions.

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Section: Introductionmentioning

confidence: 99%

Local bending stiffness identification of beams using simultaneous Fourier-series fitting and shearography

Zastavnik

Pintelon

Kersemans

et al. 2019

Journal of Sound and Vibration

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“…A temporal phase shifting is applied in order to extract the phase map from the intensity patterns. A comprehensive description of the experimental setup can be found in [5]. The measurement of a modal rotation field involves filtering and unwrapping of a phase map, as shown in Figure 3 for the case of the first modal rotation field relative to the damage scenario depicted in Figure 1(b).…”

Section: Specimen and Experimental Setupmentioning

confidence: 99%

“…In [4], it was found out that Gauss differentiation is a suitable technique to compute curvature fields from rotations measured with shearography. The problem of propagation and amplification of noise when computing derivatives was tackled by defining an optimal spatial sampling [5]. Another effective approach for post-processing measured data consists in applying various types of wavelet transforms, namely to mode shapes, which was confirmed by numerous studies [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of shearography-based damage identification using best tree wavelet packet analysis

2018

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Shearography found many industrial applications as a non-destructive testing method due to its high spatial resolution and contactless measurements. However, to detect small structural damage, shearography should be enhanced by applying advanced signal processing methods to results of experimental testing. In this paper, the authors present an enhanced method based on the best tree wavelet packet analysis, which allows for extraction of the most informative nodes from the 2D wavelet packet decomposition tree. The proposed method is more effective than typical wavelet transforms due to its ability of adaptive selection of the best basis. The efficiency of the method was verified experimentally on damaged plates. The obtained results clearly show high sensitivity to the introduced small damage, which make the method attractive for industrial applications.

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“…The method was developed in the early 1970s to solve several limitations related to interferometric holography [4,5]. Unlike other NDT methods, it is non-contact, full field, robust, and is also able to scan large areas at once without contact and allows for static and dynamic measurements with high resolution [6]. Moreover, while holography and ESPI measure surface displacement, shearography measures the derivatives of surface displacement, which leads to yield strain and strain concentration information directly [7].…”

Section: Introductionmentioning

confidence: 99%

Efficiency assessment of wavelet transforms and wavelets for damage localization in beams using shearography

et al. 2018

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Non-destructive testing of engineering structures and elements in operation is one of the crucial steps in recently introduced design philosophies: damage tolerance and condition-based maintenance. Therefore, it is important to provide effective non-destructive testing methods, which are able to detect and identify a possible damage in early stage of its development. One effective testing method, which still gains its popularity in various industrial applications, is shearography. Although, shearography is sensitive to various types of structural damage and flaws, this sensitivity can be significantly improved by applying advanced post-processing algorithms to raw data obtained from measurements. An excellent candidate for such an improvement is the wavelet analysis, due to its very high sensitivity to smallest signal disturbances. This study presents results of comparative analysis of various wavelet transforms and various wavelets in order to analyse their sensitivity to damage. The improvement in damage detectability is verified using experimental data.

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Damage identification in beams using speckle shearography and an optimal spatial sampling

Cited by 27 publications

References 25 publications

Local bending stiffness identification of beams using simultaneous Fourier-series fitting and shearography

Local bending stiffness identification of beams using simultaneous Fourier-series fitting and shearography

Enhancement of shearography-based damage identification using best tree wavelet packet analysis

Efficiency assessment of wavelet transforms and wavelets for damage localization in beams using shearography

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