Automated crack detection in laminated composites by optical flow measurements

• Published in: Composites. Part B, Engineering Vol. 255; p. 110599
• Main Authors: Nicol, Matthieu, Laurin, Frédéric, Hirsekorn, Martin, Kaminski, Myriam, Feld-Payet, Sylvia, Paulmier, Pascal, Albouy, William
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-04-2023; Elsevier
• Subjects: Engineering Sciences; Laminates; Optical microscopy; Physical methods of analysis; Physics; Polymer–matrix composites (PMCs); Transverse cracking; Polymer–matrix composites (PMCs); Optical microscopy; Laminates; Transverse cracking; Physical methods of analysis; Unidirectionnel; Détection automatique; Stratifié; Corrélation image numérique; Composite; Fissuration transverse
• ISSN: 1359-8368; 1879-1069
• DOI: 10.1016/j.compositesb.2023.110599

In this paper, an automated crack detection method for laminated composites of carbon fiber reinforced polymers (CFRP) is presented. Image correlation is performed on micrographs of the unspeckled specimen edge using DeepFlow, an algorithm for optical flow estimation. Cracks are then detected from local maxima of the displacement gradient evaluated along the midline of the plies. The detection strategy is applied to 3 different materials, with increasingly irregular microstructures, and on quasi-isotropic layups (a challenging case for crack detection). The crack density evolution in the 90∘ and ±45∘ plies is presented. The proposed method proves its capacity to detect cracks, even in complex configurations where other methods fail, and can provide an extensive amount of data that are useful for the identification of damage models for laminates. The procedure is largely automated in order to make it suitable for industrial applications.