Application of stereo vision to three-dimensional deformation analyses in fracture experiments

Journal Article · Tue Mar 01 04:00:00 EST 1994 · Optical Engineering; (United States)

OSTI ID:7235129

Luo, P F ^[1]; Chao, Y J; Sutton, M A ^[2]

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1. Chung Hua Polytechnic Inst., Hsin Chu (Taiwan, Province of China). Dept. of Mechanical Engineering
2. Univ. of South Carolina, Columbia, SC (United States). Dept. of Mechanical Engineering

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 viable tool for the 3-D deformation analysis of fracture specimens.

• OSTI ID: 7235129
• Journal Information: Optical Engineering; (United States), Journal Name: Optical Engineering; (United States) Vol. 33:3; ISSN 0091-3286; ISSN OPEGAR
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103 -- Metals & Alloys-- Mechanical Properties
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360603 -- Materials-- Properties
42 ENGINEERING
420500* -- Engineering-- Materials Testing
CALIBRATION
CAMERAS
CRACKS
DATA ACQUISITION SYSTEMS
DISPLACEMENT GAGES
FRACTURE MECHANICS
MATERIALS
MATERIALS TESTING
MEASURING INSTRUMENTS
MEASURING METHODS
MECHANICS
TESTING