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Proceedings Paper

Shearographic NDT of joined surfaces using multiple-frequency sweep
Author(s): Y.Y. Hung; Huai Min Shang
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Paper Abstract

Shearography, which enables direct measurement of surface slopes under lax environmental stability, is a practical optical tool for measurement and inspection. When applied to flaw detection, conventional shearography requires recording of two sheared-images of the test structure using an image- shearing camera - one before and another after the application of quasi-static load-increment. The resulting phase-change will be perturbed at the region where a flaw is present, when compared with that of a defect-free identical test structure. With time-average shearography, the test object is subjected to vibration excitation, and this is useful for inspection open-boundaries delaminations. A major drawback with the use of single excitation frequency is the need to vibrate the test object within an appropriate frequency range, as otherwise the test data obtained will not readily reveal the defect. This paper describes a new method, based on the use of multiple frequency sweep, which addresses this concern. The Diagnostic Map that is proposed in this paper also enables rapid detection and unambiguous assessment of the soundness of adhesive and mechanically fastened joints. Thus, the user can conduct test with little training received.

Paper Details

Date Published: 13 June 2001
PDF: 6 pages
Proc. SPIE 4317, Second International Conference on Experimental Mechanics, (13 June 2001); doi: 10.1117/12.429594
Show Author Affiliations
Y.Y. Hung, National Univ. of Singapore (United States)
Huai Min Shang, National Univ. of Singapore (Singapore)


Published in SPIE Proceedings Vol. 4317:
Second International Conference on Experimental Mechanics

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