Dual-mode sensor array for eddy current & capacitive NDE of FRP composites

This paper presents a dual-mode concentrical sensor for flaw detection in fiber-reinforced polymer (FRP) composites using eddy current testing (ECT) and capacitive imaging (CI). Combining ECT and CI techniques provides the necessary synergy to detect damage in both electrically conductive and insulative FRP materials. The proposed sensor, featuring rotational symmetry, comprises a central pancake coil and an outer ring coil, both printed on a multi-layered printed circuit board (PCB). When configured for ECT, the coils serve as a means for magnetic field excitation and pickup, while in CI mode, the central pancake coil and the outer ring coil function as charged electrodes of the disk-and-ring capacitor. A dual-mode array probe is created using staggered linear arrays of individual sensors. Experimental validation involves interfacing the array with the Fanuc robotic arm and the Ectane 2 multichannel data acquisition system. Initial results show the capability to detect volumetric flaws, fiber breakage, and interlaminar delaminations in carbon FRP.