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Mechanical assessment of defects in welded joints: morphological classification and data augmentation

Abstract : We develop a methodology for classifying defects based on their morphology and induced mechanical response. The proposed approach is fairly general and relies on morphological operators (Angulo & Meyer, 2009) and spherical harmonic decomposition as a way to characterize the geometry of the pores, and on the Grassman distance evaluated on FFT-based computations (Willot, 2015), for the predicted elastic response. We implement and detail our approach on a set of trapped gas pores observed in X-ray tomography of welded joints, that significantly alter the mechanical reliability of these materials (Lacourt et al, 2020). The space of morphological and mechanical responses is first partitioned into clusters using the “k-medoids” criterion and associated distance functions. Second, we use multiple-layer perceptron neural networks to associate a defect and corresponding morphological representation to its mechanical response. It is found that the method provides accurate mechanical predictions if the training data contains a sufficient number of defects representing each mechanical class. To do so, we supplement the original set of defects by data augmentation techniques. Artificially-generated pore shapes are obtained using the spherical harmonic decomposition and a singular value decomposition performed on the pores signed distance transform. We discuss possible applications of the present method, and how medoids and their associated mechanical response may be used to provide a natural basis for reduced-order models and hyper-reduction techniques, in which the mechanical effects of defects and structures are decorrelated (Ryckelynck et al, 2020).
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https://hal.archives-ouvertes.fr/hal-03417140
Contributor : David Ryckelynck Connect in order to contact the contributor
Submitted on : Thursday, November 25, 2021 - 11:46:29 AM
Last modification on : Saturday, October 22, 2022 - 5:19:55 AM
Long-term archiving on: : Saturday, February 26, 2022 - 6:41:34 PM

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Hugo Launay, François Willot, David Ryckelynck, Jacques Besson. Mechanical assessment of defects in welded joints: morphological classification and data augmentation. Journal of Mathematics in Industry, 2021, 11 (8), pp.18. ⟨10.1186/s13362-021-00114-7⟩. ⟨hal-03417140⟩

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