New optical strain method of three-beams interferometry and digital image processing

L. A. Li; Z. Y. Wang; S. B. Wang; P. Goudeau; J. W. Tong

doi:10.1117/12.621900

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12 April 2005 New optical strain method of three-beams interferometry and digital image processing

L. A. Li, Z. Y. Wang, S. B. Wang, P. Goudeau, J. W. Tong

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Proceedings Volume 5852, Third International Conference on Experimental Mechanics and Third Conference of the Asian Committee on Experimental Mechanics; (2005) https://doi.org/10.1117/12.621900
Event: Third International Conference on Experimental Mechanics and Third Conference of the Asian Committee on Experimental Mechanics, 2004, -, Singapore

Abstract

Based on the optical diffraction and interference, a new method of digital image processing is presented for the in-plane strain measurements in macro and micro-zone. The principle of the improved moire interferometry and the algorithm are presented in this paper. In this study, the cross grating of the frequency of 1200 l/mm is replicated on the specimen surface. Three coherent laser beams are used to obtain the U+V and U-V fringe patterns. Combining the FFT phase shift technique and subpixel technique, the displacement components U and V are calculated with the high precision. The new method has some advantages, such as simple optical arrangement, direct calculation of U and V fields with higher precision. Using this method, the displacement and strain fields on the free-edge of the thermo-plastic composite laminates AS4/PEEK[0/±45/90]7S (56-ply) under three-point bending have been measured. The corresponding numerical simulation has been carried out using three-dimensional orthotropic elastic finite element model method. It is believed that this method will be a powerful tool in characterizing the mechanical properties of materials.

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L. A. Li, Z. Y. Wang, S. B. Wang, P. Goudeau, and J. W. Tong "New optical strain method of three-beams interferometry and digital image processing", Proc. SPIE 5852, Third International Conference on Experimental Mechanics and Third Conference of the Asian Committee on Experimental Mechanics, (12 April 2005); https://doi.org/10.1117/12.621900

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