Research on an Extraction Method of Defect Signal of Multi-Layer Joint Based on Wavelet Analysis

In order to detect the debond defect of multilayer metal-rubber adhesive joint, the mature ultrasonic detecting technique was used. By rebuilding an existing ultrasonic detecting instrument, utilizing a high speed data acquisition card and LabVIEW developing environment, an ultrasonic signal acquisition and analysis platform was successfully built. Echo signal acquisition was programmed. The signal was decompose and reconstructed utilizing db7 wavelet by Matlab script node in LabVIEW. A contrast experiment was carried out on two specimens having debond defect. The result shows that the reconstructed signals are remarkably different between areas bonded well and not, which indicates that the wavelet analysis method is effective in detecting the debond defect under the first rubber layer.