Defect Detection Using the Lamb Mode S0 by Pulsed Laser Laterally Illuminating on a Side of the Plate
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In recent years, Lamb waves have been widely used to inspect plate-like structures, where antisymmetric modes are usually applied due to their high out-of-plane displacement and long propagating distance under normal circumstances. However, their dispersive behavior and leakage character in liquid-loaded plates make them unable to distinguish defects in some cases. In this paper, the pure S0 mode with a high amplitude and small dispersion is generated, which is implemented by a pulsed laser laterally illuminating on a side of the plate symmetrically. Experiments are carried out in a 0.2 mm aluminum plate. The experimental result shows strong agreement with simulation, which indicates that this method can restrain the A0 mode and improve the S0 mode efficiently. Moreover, experimental measurements for defect detection in the plates fully immersed in water are carried out preliminarily. These results indicate that this optical method for generating the pure S0 mode could be useful for defect detection in air and underwater conditions.
KeywordsLamb wave Laser ultrasound NDE S0 mode
This study was supported by the National Natural Science Foundation of China (Grant Nos. 11274175 and 61405093), Natural Science Foundation of Jiangsu Province (Grant No. BK20140771).
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