High-speed inspection of UD CFRP composites

M A Machado, K-N Antin, L S Rosado, P Vilaça and T G Santos 

Online monitoring of carbon fibre-reinforced polymer (CFRP) components requires a non-destructive testing (NDT) method capable of contactless sensing of damage, while enabling the high inspection speeds needed for monitoring large components. Eddy current testing (ECT) of CFRP components has great potential for two reasons. First, ECT probes are capable of operating without contact, although minimising the lift-off is preferred. Second, impedance analysers with high sample rates make high-speed inspection possible. This research assesses the damage detection capabilities of eddy current probes on CFRP samples with artificial and realistic damage. To support the aptitude of the ECT method for these needs, the CFRP material is characterised and numerical simulations are performed in order to develop optimised and tailored ECT probes for the detection of defects with different morphologies, namely fibre breakage and delaminations, and to take into consideration the highly anisotropic electrical bulk resistivity of the CFRP material. Different ECT probes were designed, produced and experimentally validated. The experiments were performed at a high inspection speed (4 m/s) and the high sensitivity of the probes was demonstrated.