Ultrasonic inspection of adhesively bonded CFRP/aluminum joints using pulsed laser scanning

In this study, we propose an ultrasonic inspection technique for detecting disbonds in adhesively bonded carbon fiber-reinforced plastics (CFRP)/aluminum joints using pulsed laser scanning. A specimen with artificially induced square disbonds was scanned by a pulsed laser for ultrasound generation, and the propagating waves were received by a transducer placed on its surface. A series of images of the traveling waves were obtained by processing the received signals. An initial, quick inspection was performed using low-frequency Lamb waves. Changes in the propagation of the Lamb waves were observed at the disbond regions, and disbonds larger than 5 x 5 mm(2) were successfully detected. A second, detailed inspection of the detected disbond regions was performed using the high-frequency through-transmission ultrasonic method. The shape of the disbond was precisely imaged, and the evaluated size of the disbond matched well with the actual size. We thus demonstrated the efficiency and the feasibility of the proposed technique for the inspection of adhesively bonded CFRP/Al joints.