Eddy Current Nondestructive Testing for Carbon Fiber-Reinforced Composites

This paper describes the use of an eddy current testing (ECT) method for the inspection and detection of impact damage in carbon fiber-reinforced composites (CFRP). ECT method is a nondestructive testing (NDT) method where electric induction is used. This method is widely used for detecting cracks and corrosion in metals, or checking their electric conductivity. Because carbon fiber in CFRP has electric conductivity, ECT method has a potential to inspect the defects. However, electric conductivity of CFRP is much smaller than that of metals. Moreover, from the view of the eddy current probe, CFRP to be checked looks as a inhomogeneous conductive materials where conductive fibers are bundled and laid up, and this is completely different situation comparing with metal samples that are homogeneous. Therefore, there are several problems to be solved for applying ECT method to CFRP such as proper selection of test frequency, shape of probe, or signal processing.