Abstract
The variation in Mode I stress-intensity factor throughout the thickness of an ASTM standard compact tension specimen was determined using scattered-light speckle interferometry. Two very thin sheets of coincident coherent light traveling in opposite directions were passed through a Plexiglas specimen normal to the crack faces. A double-exposed photograph of the scattered-light speckle pattern was taken while the specimen was subjected to a small load increment. From this double-exposed photograph, the change in the crack-opening displacement could be determined. From the information about the crack-opening displacement in the region of the crack tip, the stress-intensity factor was calculated for various interior planes and on the surface of the specimen. For the compact tension specimen tested, the stress-intensity factor did not vary throughout the specimen's thickness. The method of scattered-light speckle interferometry proved to be very powerful in solving this complex three-dimensional problem.
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Research funded by National Science Foundation Grant #GK-40012.
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Barker, D.B., Fourney, M.E. Three-dimensional speckle interferometric investigation of the stress-intensity factor along a crack front. Experimental Mechanics 17, 241–247 (1977). https://doi.org/10.1007/BF02324837
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DOI: https://doi.org/10.1007/BF02324837