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Proceedings Paper

Study of the fracture process using laser holographic interferometry and image analysis
Author(s): Alberto Castro-Montero; Surendra P. Shah; Hans I. Bjelkhagen
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Paper Abstract

The fracture process on cement based materials was studied using various holographic interferometry methods. Several aspects of the fracture process were studied on plane mortar (cement water and sand) and polypropylene fiber reinforced cement under different loading configurations. Sandwich holography was used to analyze mortar specimens loaded in tension. The real time method was used to determine the load increments required for accurate and easy evaluation of displacements. A single sensitivity vector setup was used for the evaluation of crack opening displacements and a multiple sensitivity vector set-up was used for the evaluation of full displacement fields. In both cases the holographic images were acquired by a digital image analysis system. First the images were enhanced for better recognition of the fringe patterns by elimination of high frequency noise and contrast improvement. Then the image analysis system was used for automatic fringe count. Sandwich holographic interferometry was also used to map the crack surfaces of the mortar specimens tested. The use of image analysis was essential for the evaluation of the interferograms. The image analysis system allowed for the direct application of a moire pattern method resulting in topographic contour maps. Crack pattern characterization on polypropylene fiber reinforced specimens was made using the ''piggy back'' method to record double exposure reflection holograms. Image processing was used for image enhancement and automatic computation of crack spacings. 1.

Paper Details

Date Published: 1 March 1991
PDF: 9 pages
Proc. SPIE 1396, Applications of Optical Engineering: Proceedings of OE/Midwest '90, (1 March 1991);
Show Author Affiliations
Alberto Castro-Montero, Northwestern Univ. (United States)
Surendra P. Shah, Northwestern Univ. (United States)
Hans I. Bjelkhagen, Northwestern Univ. (United States)

Published in SPIE Proceedings Vol. 1396:
Applications of Optical Engineering: Proceedings of OE/Midwest '90
Rudolph P. Guzik; Hans E. Eppinger; Richard E. Gillespie; Mary Kathryn Dubiel; James E. Pearson, Editor(s)

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