Crack Profile Reconstruction of CFRP-CFRP Bonded Joints from Optical Backscatter Reflectometry and Comparison with X-Ray Computed Tomography

Adhesive bonding is one of the most suitable joining technique for composite lightweight structures, allowing lower stress concentration in the substrates, thus reducing the dimensions and the weight of connections. In adhesive joints, the Back Face strain method is often used as an effective SHM technique, where, dealing with single lap joints, the BF strain displays a characteristic negative peak caused by the rotation of the joint whose position varies if a crack is propagating within the adhesive. In this work, the Optical Backscatter Reflectometry (OBR), i.e. a distributed sensing technique, is used to monitor fatigue crack growth damage of woven CFRP-CFRP single lap bonded joints. Crack profile reconstructions from the BF strain peak profile recorded by distributed fiber sensing technology are here reported and referenced with X-Ray CT reconstructions.