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Proceedings Paper

Evaluation of fatigue damage using laser speckle: relation between surface profile and diffraction pattern
Author(s): Akira Kato; Fumihiko Okuya
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Paper Abstract

We investigated a method to evaluate fatigue damage of steels without contact using laser speckle. In the earlier stage of fatigue in steels, slipbands appear on the surface and microscopic phase strain is stored in the slipbands. The slipbands appear more densely with progress of fatigue damage. When a laser illuminates surface of the fatigued steel, light intensity distribution of the laser speckle pattern formed by the reflected light changes with the change of surface properties caused by slipbands. It has been clarified that width of the speckle pattern broadens corresponding to spatial frequency distribution of the surface profile and thus it is presumed that speckle pattern broadness with increase of slipband density. This shows that we can detect fatigue damage by observing the laser speckle pattern broadens with increase of slipband density. This shows that we can detect fatigue damage by observing the laser speckle pattern on material surface. The method presented in this paper is based on this phenomenon. We observed change of surface property and the speckle pattern during fatigue loading under constant stress amplitude using steel specimens. Surface roughness and fractal analysis of the surface profile diagrams were obtained to evaluate surface property. Change of surface roughness and fractal dimension of the surface profile were compared to change of laser speckle pattern depending on progress of fatigue damage and relation between surface property and speckle pattern was investigated. We investigated possibility of evaluation of fatigue damage observing laser speckle pattern during fatigue.

Paper Details

Date Published: 13 June 2001
PDF: 6 pages
Proc. SPIE 4317, Second International Conference on Experimental Mechanics, (13 June 2001); doi: 10.1117/12.429605
Show Author Affiliations
Akira Kato, Chubu Univ. (Japan)
Fumihiko Okuya, Chubu Univ. (Japan)

Published in SPIE Proceedings Vol. 4317:
Second International Conference on Experimental Mechanics
Fook Siong Chau; Chenggen Quan, Editor(s)

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