Delamination Detection in Bimetallic Composite Using Laser Ultrasonic Bulk Waves

Featured Application This paper presents a testing method based on laser ultrasonic bulk waves for the detection of interface delamination defects in a Cu/Al bimetallic plate produced by sandwich rolling. In this study, a method based on laser ultrasonic bulk waves is used to detect delamination in a bimetallic composite. For this purpose, several artificial delamination defects were created in a copper-aluminum sample using wire-electrode cutting. The research includes numerical simulation and experimental analysis. The propagation process of laser ultrasonic in Cu/Al bimetallic compo-site, the interaction between bulk waves and composite interface, and the effect of delamination defects on the ultrasound field were studied by numerical simulation. Suitable parameters and features were determined by numerical simulation, which provided a basis for the parameter se-lection of experimental research. The reflected shear waves from the composite interface can act as a sensitive feature to detect the delamination in Cu/Al bimetallic composites. The distance between the detection point and the excitation point was set to 2 mm to take into account the detection resolution and efficiency. The experimental results were in good agreement with the simulation results, and the C-scan image can intuitively show the location and size of delamination defects. The detection method based on laser ultrasonic bulk waves can effectively detect the delamination in Cu/Al bimetallic composite, which is suitable for the on-line detection of the rolling composite process.