Detection of Fiber Waviness inside CFRP and an Evaluation of the Effect on Fracture Using X-ray Talbot-Lau Interferometer

• Published in: Journal of the Japan Society for Composite Materials Vol. 50; no. 1; pp. 19 - 24
• Main Authors: ISHIKAWA, Lisa, DOKI, Takahiro, MORIMOTO, Naoki, KIMURA, Kenji, MATSUKURA, Izumi, KOBIKI, Akira
• Format: Journal Article
• Language: English
• Published: The Japan Society for Composite Materials 15.01.2024
• Subjects: CFRP; Computed tomography; Out-of-plane waviness; Talbot-Lau interferometer; X-ray
• ISSN: 0385-2563; 1884-8559
• DOI: 10.6089/jscm.50.19

Chopped carbon fiber tape reinforced thermoplastics (CTT) have recently attracted attention owing to their excellent moldability. However, internal fiber waviness may occur depending on the molding conditions, such as the material charging pattern. Large out-of-plane waviness is known to be a strength reduction factor, and method for non-destructive observation of the out-of-plane waviness is necessary. Herein, a method was developed to detect the location and degree of fiber out-of-plane waviness using scattering Computed Tomography (CT) images acquired via X-ray Talbot-Lau interferometry. X-ray Talbot-Lau interferometer is equipped with diffraction gratings for detecting small-angle X-ray scattering, and hence, fiber information can be acquired with a wider field of view than that via conventional X-ray CT. Out-of-plane waviness was extracted from the evaluation samples; tensile testing and cross-sectional observation confirmed that fracture occurred at the location with large out-of-plane waviness. These results suggest that out-of-plane waviness can be used as a parameter to improve the accuracy of predicting the strength reduction location.