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摘要
In order to improve the efficiency of ultrasonic non-destructive inspection of bonded structures, the study of inspectionmethod based on the air-coupled ultrasonic Lamb wave technology was conducted for quick non-contact inspecting for bonded structure of SRM. The propagation process of Lamb wave in the bonded structure was simulated by using same-sideLamb wave method. The effects of different defect sizes on the signal amplitude and the sensitivity of different modes of Lamb wave to defects were analyzed by means of simulation and experiment.Meanwhile, defects of different sizes were detected by using opposite-sideLamb wave method.The amplitude curve of the debonding area was obtained by using the orthogonal direction line scanning signal acquisition method, and the defect was quantified by 6 dB method. Same-sideLamb wave damage probability algorithm and opposite-sideLamb wave automatic scanning technology were used to locate and image the defects, and C-scan was used to verify the results.The results show that the amplitude of the same-side Lamb wave increases with the increase of defect size, and the simulation results are basically consistent with the experimental results. The high sensitivity Lamb wave mode has a large large off-surface displacement component. The presence of defects in the use of aopposite-sideLamb wave will result in a sharp attenuation of the signal energy. Using the 6 dB method, the error is smaller when the defect size is larger, and the error is larger when the defect size is smaller. In general, the amplitude trend curve can characterize the defect area.Probabilistic imaging and opposite-sideLamb wave automatic scanning technology can locate the defects quickly and effectively, and the defect contour is clear. Compared with C-scan imaging, the imaging quality is improved.The research content provides a good foundation for the actual detection of air-coupled ultrasound.
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