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20 July 2004 A model for the ultrasonic detection of surface-breaking cracks by the scanning laser-source technique
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Abstract
A model for the Scanning Laser Source (SLS) technique is presented. The SLS is a novel laser based inspection method for the ultrasonic detection of small surface-breaking cracks. The generated ultrasonic signal is monitored as a line-focused laser is scanned over the defect. Characteristic changes in the amplitude and the frequency content are observed. The modelling approach is based on the decomposition of the field generated by the laser in a cracked two-dimensional half-space, by virtue of linear superposition, into the incident and the scattered fields. The incident field is that generated by laser illumination of a defect-free half-space. A thermoelastic model has been used which takes account of the effect of thermal diffusion, as well as the finite width and duration of the laser source. The scattered field incorporates the interactions of the incident field with the surface-breaking crack. It has been analyzed numerically by a direct frequency domain boundary element method. A comparison with an experiment for a large defect shows that the model captures the observed phenomena.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Irene Arias and Jan D. Achenbach "A model for the ultrasonic detection of surface-breaking cracks by the scanning laser-source technique", Proc. SPIE 5393, Nondestructive Evaluation and Health Monitoring of Aerospace Materials and Composites III, (20 July 2004); https://doi.org/10.1117/12.540109
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