Numerical Simulation Study of Defect Detections by Using Laser Array Generated Giant Acoustic Waves
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Based on the classical theory of laser ultrasound generation in a thermoelastic regime, the generation of ultrasound by laser array source irradiation is simulated by the finite element method. The propagation and interaction of the laser-generated ultrasound with a bulk defect are studied. By changing the trigger time delay of a spatially evenly distributed laser array source, giant bulk waves with specific wavefronts and amplitudes several times larger than those of waves generated by a single laser source can be obtained. The interaction between giant acoustic waves and a bulk defect is compared with that in the model without the defect obtained under the same conditions. Results show that compared with a single-pulse generated acoustic wave, the detectability of multiple-source generated giant acoustic waves to defects can be improved significantly.
KeywordsFinite element method Laser array source Laser ultrasonics Micro-crack
This paper is supported by the National Natural Science Foundation of China under Grant No. 61405093, the Natural Science Foundation of Jiangsu Province under Grant No. BK20140771, and financial support for the start-up scientific research of Nanjing University of Science and Technology.
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