Lamb wave mode scattering analysis on adhesively bonded single lap joint using modal decomposition method

Šofer, Michal; Šofer, Pavel; Ferfecki, Petr; Molčan, M.; Stryja, Jakub

doi:10.1016/j.apm.2020.08.017

Cited by 6 publications

(5 citation statements)

References 40 publications

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“…Symmetric modes are also known as quasi-extensional modes because they have a dominant wave polarization component along the propagation of the wave. In contrast, antisymmetric modes (or flexural modes) have quasi-flexural behavior, and they can be mathematically defined as follows (Šofer et al 2021 ): …”

Section: Methodsmentioning

confidence: 99%

Ultrasonic tomography imaging enhancement approach based on deep convolutional neural networks

Malikov

Cuenca

Kim

et al. 2023

J Vis

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The containment liner plate (CLP) is a thin layer of carbon steel material applied as a base for concrete structures protecting nuclear material. The structural health monitoring of the CLP is critical to ensure the safety of nuclear power plants. Hidden defects in the CLP can be identified utilizing ultrasonic tomographic imaging techniques such as the reconstruction algorithm for the probabilistic inspection of damage (RAPID) methodology. However, Lamb waves have a multimodal dispersion feature, which makes the selection of a single mode more difficult. Thus, sensitivity analysis was utilized since it allows for the determination of each mode's level of sensitivity as a function of frequency; the S0 mode was chosen after examining the sensitivity. Even though proper Lamb wave mode was selected, the tomographic image had blurred zones. Blurring reduces the precision of an ultrasonic image and makes it more difficult to distinguish the dimensions of the flaw. To enhance the tomographic image of the CLP, deep learning architecture such as U-Net was utilized for the segmentation of the experimental ultrasonic tomographic image, which includes an encoder and decoder part for better visualization of the tomographic image. Nevertheless, collecting enough ultrasonic images to train the U-Net model was not economically feasible, and only a small number of the CLP specimens can be tested. Thus, it was necessary to utilize transfer learning and get the values of the parameters from a pre-trained model with a much larger dataset as a starting point for a new task, rather than training a new model from scratch. Through these deep learning approaches, we were able to eliminate the blurred section of the ultrasonic tomography, leading to images with clear edges of defects and no blurred zones. Graphical abstract

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Section: Methodsmentioning

confidence: 99%

Ultrasonic tomography imaging enhancement approach based on deep convolutional neural networks

Malikov

Cuenca

Kim

et al. 2023

J Vis

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“…where | t hm denotes the integration over the specified sub-waveguide thickness in the form of the given inner product. After the rearrangement of Equations ( 17)-( 20) [43,44], we can derive the explicit formulation of the global scattering matrix, a linear operator, which links the vectors containing the complex amplitudes of the reflected waves…”

Section: Scattering Of Lamb Waves At Vertical Notchmentioning

confidence: 99%

“…In the next step, both methods, i.e., semi-analytical and hybrid approaches, were then used to evaluate the energy scattering coefficients for selected fractions of reflected or transmitted energy of A 0 mode in sub-waveguide 3. In the case of the semi-analytical approach, the analysis began with the identification of real, imaginary, and complex wavenumbers [45], including an additional refinement procedure based on the Newton-Raphson method, in which the complex wavenumbers have to be considered in the form of conjugate pairs [44]. Feng et al [46] proved that the best results are obtained when the number of wavenumbers corresponding to S modes NS is higher by one compared to the number of A modes NA, i.e., NS = NA + 1.…”

Section: Numerical Verification Of Pet Modelmentioning

confidence: 99%

Partial Energy Transfer Model of Lamb Waves Scattering in Materially Isotropic Waveguides

Šofer

Raček

et al. 2021

Applied Sciences

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The scattering phenomena of the fundamental antisymmetric Lamb wave mode with a horizontal notch enabling the partial energy transfer (PET) option is addressed in this paper. The PET functionality for a given waveguide is realized using the material interface. The energy scattering coefficients are identified using two methods, namely, a hybrid approach, which utilizes the finite element method (FEM) and the general orthogonality relation, and the semi-analytical approach, which combines the modal expansion technique with the orthogonal property of Lamb waves. Using the stress and displacement continuity conditions on the present (sub)waveguide interfaces, one can explicitly derive the global scattering matrix, which allows detailed analysis of the scattering process across the considered interfaces. Both methods are then adopted on a simple representation of a surface breaking crack in the form of a vertical notch, of which a certain section enables not only the reflection of the incident energy, but also its nonzero transfer. The presented results show very good conformity between both utilized approaches, thus leading to further development of an alternative technique.

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“…The given method also supports localization of the Ae sources using an array of sensors, which is a significant benefit for many industrial applications, where we encounter thin-walled geometries. The plate-like character enables the transformation of the initial voluminal waves into rayleigh or Lamb guided waves [4,5], which exhibit dispersion [6,7] and thus the Ae signal processing methodology is an integral part of the measurement procedure.…”

Section: Introductionmentioning

confidence: 99%

Application of Improved b-Value and Clustering Analysis for Structural Integrity Assessment of CFRP Specimen under Tensile Loading

Šofer,

Kwiatoń,

Pavlíček

2023

Archives of Metallurgy and Materials

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ApplicAtion of improved b-vAlue And clustering AnAlysis for structurAl integrity Assessment of cfrp specimen under tensile loAdingIn the present study, the evolution of different failure mechanisms in carbon fiber reinforced polymer composites is being investigated using acoustic emission technique, unsupervised clustering technique and improved b-value analysis. The experimental part involved the realization of tensile tests of different materials, namely samples with [0/90] 2S uniaxial layer configuration and [0/90] 2S twill fabric samples. Both types of tests were monitored using one wideband acoustic emission sensor, while the tensile tests of twill fabric samples were additionally supplemented with resonant acoustic emission sensor to perform a comparative analysis between datasets from resonant/wideband acoustic emission sensor. The comparative study itself was preceded by the failure mechanisms characterization process, which has been performed on the tensile test dataset of [0/90] 2S layer configuration with the contribution of clustering technique. The subsequent analysis of the twill fabric resonant/wideband acoustic emission sensor datasets included the improved b-value technique, which relates the magnitude of fracture with the slope of the amplitude distribution. The presented results, especially in terms of the improved b-value technique applied to individual clusters, show enhanced ability to assess in more detail the actual structural integrity depending on the applied load.

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Lamb wave mode scattering analysis on adhesively bonded single lap joint using modal decomposition method

Cited by 6 publications

References 40 publications

Ultrasonic tomography imaging enhancement approach based on deep convolutional neural networks

Ultrasonic tomography imaging enhancement approach based on deep convolutional neural networks

Partial Energy Transfer Model of Lamb Waves Scattering in Materially Isotropic Waveguides

Application of Improved b-Value and Clustering Analysis for Structural Integrity Assessment of CFRP Specimen under Tensile Loading

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