Rotating Field Eddy Current Imaging for the Non-Destructive Evaluation of Buried and Oriented Defects 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 (2 mm to 10 mm), and buried down to 6 mm 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.