Nondestructive analysis of debonding in composite/rubber/rubber structure using ultrasonic pulse-echo method

Detecting the debonding defects in the composite/rubber/rubber bonding structure is very difficult because of the high attenuation and aliasing of the ultrasonic wave from the structure. In order to solve this problem, a detection system was built based on the high-power ultrasonic pulse-echo method, and the time-frequency contour image of the wavelet coefficient modulus of the echo using wavelet transform was drawn. Through these, the characteristic parameters were clearly extracted which can represent the defects' sizes and positions, and build the debonding defect parameter database. Based on this database, two defect evaluation algorithms are proposed and their accuracy is verified. Results show that the minimum Euclidean distance method can detect the defect diameter with an average deviation of 1 mm, a maximum deviation of 3 mm, and can realise accurate positioning of the testing defect. Based on the echo's high attenuation and aliasing, this paper provides a solution for the ultrasonic detection of debonding defects in multi-layer structures,and verifies their feasibility and accuracy.