Noncontact Characterization of Carbon-Fiber-Reinforced Plastics Using Multifrequency Eddy Current Sensors

The characterization of carbon-fiber-reinforced plastics (CFRPs) using multifrequency eddy current (sensors is presented in this paper. Three sensors are designed for bulk conductivity measurements, directionality characterization, and fault detection and imaging of unidirection, cross-ply, and impact-damaged CFRP samples. Analytical and finite-element (FE) models describing the interaction of the sensors with the CFRP plate samples are developed to provide an explanation of, and physical insights into, the measured results and observed phenomena. A signal processing method is developed to compensate for the variation in lift-off during the measurements.