ROTATING FIELD EDDY CURRENT IMAGING FOR THE NDE OF BURIED AND ORIENTED DEFECTS BURIED IN RIVETED LAP-JOINTS

An eddy current imager based on a linear magneto-optical imaging system is presented and implemented for the non-destructive inspection of defects buried in aeronautical riveted lap-joints. Defects of various orientation (-20° to 90°) and length (2mm to 10mm), and buried down to 6mm closely to the rivets in a lap-joint coupon are inspected and analyzed. The provided EC images are processed thanks to a proposed source separation technique involving multi-frequency and multi-orientation images. The proposed image processing enables the quantitative characterization of the defects relatively to their length, depth and orientation