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Optical Engineering

Application of stereo vision to three-dimensional deformation analyses in fracture experiments
Author(s): Perng-Fei Luo; Yuh J. Chao; Michael A. Sutton
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Paper Abstract

Based on a pinhole camera model, camera model equations that account for the radial lens distortion are used to map three-dimensional (3-D) world coordinates to two-dimensional (2-D) computer image coordinates. Using two cameras to form a stereo vision, the 3-D information can be obtained. It is demonstrated that such stereo imaging systems can be used to measure the 3-D displacement field around the crack tip of a fracture specimen. To compare with the available 2-D theory of fracture mechanics, the measured displacement fields expressed in the world coordinates are converted, through coordinate transformations, to the displacement fields expressed in specimen crack tip coordinates. By using a smoothing technique, the in-plane displacement components are smoothed and the total strains are obtained. Rigid body motion is eliminated from the smoothed in-plane displacement components and unsmoothed out-of-plane displacement. Compared with the theoretical elastic-plastic field at a crack tip, the results appear to be consistent with expected trends, which indicates that the stereo imaging system is a viable tool for the 3-D deformation analysis of fracture specimens.

Paper Details

Date Published: 1 March 1994
PDF: 10 pages
Opt. Eng. 33(3) doi: 10.1117/12.160877
Published in: Optical Engineering Volume 33, Issue 3
Show Author Affiliations
Perng-Fei Luo, Chung Hua Polytechnic Inst. (Taiwan)
Yuh J. Chao, Univ. of South Carolina (United States)
Michael A. Sutton, Univ. of South Carolina (United States)

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