Assessment of planar NDE methods for damage in open hole carbon fibre laminates

This study evaluates the sensitivity of non-destructive imaging methods to characterise in-plane (delaminations) and out-of-plane (matrix cracking/splitting) damage in open-hole carbon fibre reinforced polymer (CFRP) angle-ply specimens as a function of tensile loading to 86% and 97% of the ultimate tensile stress (UTS). Ultrasound, X-ray radiography (with and without contrast agent), and X-ray phase contrast imaging (XPCi) are compared against X-ray computed tomography (XCT). XPCi shows good sensitivity to out-of-plane (transverse) matrix cracks without the need for a contrast agent but has limited ability to assess in-plane delaminations. Conversely, ultrasonic C-scan demonstrated good accuracy for the quantification and depth estimation of in-plane delaminations, being comparable to segmented XCT data. A combination of ultrasound and XPCi could potentially allow planar NDE of delamination and matrix cracking without the access, throughput, and size limitations inherent in computed tomography or the need for invasive and expensive contrast agents required for radiographic imaging.