• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.2
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• pp.122-129
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• 2006

Shearography is one of optical methods that has been applied to nondestructive testing (NDT) and strain/stress analysis. The technique has the merit of the directly measuring relative displacement, which is insensitive to environmental vibration disturbance. Previous studies about the method have emphasized on extending its application to new fields and lack insufficient research on effective parameters for qualitative and quantitative evaluation of defects. In this paper, the influence of shearing amount on the detection of an internal defect is investigated. In experiment, slender defects along longitudinal direction of pipeline are artificially designed and detection results according to the change of shearing amount are analyzed. Based on the investigation, we propose the technique for the determination of defect size and accurate source location.