Reflective fringe pattern technique for non-destructive subsurface flaw detection
This paper presents a novel optical technique, Reflective Fringe Pattern (RFP), for non-destructive testing of objects having specularly or semi-specularly reflective surfaces. The principles are based on measuring the surface deformation of a test object and identifying deformation
anomalies caused by subsurface flaws. In the set-up, a computer-generated fringe pattern displayed on a computer monitor is placed in front of the test object surface (which acts as a mirror) and forms a mirror image of the fringe pattern. The fringe pattern is perturbed according to the surface
slope distribution. In the measurement, the fringe phase distributions before and after deformation are separately determined, and the difference of the phase distributions depicts the change of surface slope due to the deformation. In this paper, experimental demonstrations of the present
technique to subsurface crack detection and adhesive bonding evaluation are presented. Two methods are also designed to enhance the flaw visibility on the output of RFP.
Keywords: Non-destructive; adhesive bonding evaluation; disbands; reflective grating; subsurface cracks; subsurface flaw
Document Type: Research Article
Affiliations: Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong. fionabobo2004yahoo.com.hk
Publication date: 01 October 2008
- Official Journal of The British Institute of Non-Destructive Testing - includes original research and development papers, technical and scientific reviews and case studies in the fields of NDT and CM.
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