The possibility of increasing the sensitivity and efficiency of adhesive bond inspection by utilizing ultrasonic Lamb waves in a contact mode is demonstrated. Both Pulse-Echo and Through Transmission type transducer arrangements are considered. The basic theory behind both techniques is addressed and experiments are performed on several different specimens of aluminium to aluminium adhesively bonded lap joint structures containing programmed debond simulations. It is shown that if the proper ultrasonic inspection parameters such as transducer frequency and incident angle are chosen to efficiently generate a specific Lamb wave mode, a map of the amplitude of the transmitted or reflected Lamb wave can serve to locate the debond regions within the bondline. The typical difference in the amplitude of the reflected and/or transmitted Lamb waves from good to bad regions is above 25 dB. The increase in inspection efficiency of the current Lamb wave technique over the conventional point by point normal incidence longitudinal and/or shear wave techniques is also discussed.
|Original language||English (US)|
|Number of pages||4|
|Journal||British Journal of Non-Destructive Testing|
|State||Published - Dec 1 1992|
All Science Journal Classification (ASJC) codes