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Proceedings Paper

Noncontact NDE of microscopic surface-breaking cracks using laser generated and detected ultrasonic surface waves
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Paper Abstract

Laser ultrasonic imaging of surface acoustic waves on a material surface provides a non-contact and sensitive method for detecting and characterizing defects and anomalies in aerospace and industrial materials. It has recently been shown that the surface acoustic wave interactions with sharp material discontinuities such as surface-breaking cracks provides an additional benefit of an intensification of the displacement field in the immediate vicinity of the crack site. This near-field intensification can be exploited by scanning, point-by-point, a laser-ultrasonic system to create detailed microscopic images of the surface breaking cracks. In this effort, a number of laser ultrasonic system parameters were studied to better understand the optimized conditions to imaging surface breaking cracks using ultrasonic generation in the thermoelastic regime, and laser detection of ultrasound fields using heterodyne interferometer. In particular, laser beam sizes, separation distances, and motives were varied. In addition, several different time-gating analysis methods were studied, which had a significant effect on both the characteristics as well as the quality of the resultant crack images.

Paper Details

Date Published: 20 July 2004
PDF: 12 pages
Proc. SPIE 5393, Nondestructive Evaluation and Health Monitoring of Aerospace Materials and Composites III, (20 July 2004); doi: 10.1117/12.538928
Show Author Affiliations
Adam Cooney, Univ. of Dayton (United States)
James L. Blackshire, Air Force Research Lab. (United States)

Published in SPIE Proceedings Vol. 5393:
Nondestructive Evaluation and Health Monitoring of Aerospace Materials and Composites III
Peter J. Shull; Andrew L. Gyekenyesi, Editor(s)

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