Date of Graduation

2001

Document Type

Thesis

Degree Type

MS

Committee Chair

Bruce Kang

Abstract

Recent research advancement of moiré interferometry has incorporated phase shifting, a technique for better accuracy and easier digital image processing. However, moiré interferometry with phase shifting also revealed some sensitivity problems. Background noise associated with the topography of the specimen and optical effect produces rough and discontinuous displacement fields, which makes it difficult to obtain accurate strains and stresses. In this research, two alternate methods that improve the sensitivity of moiré interferometry, with and without phase shifting is developed. The result is a smoother displacement fields with higher sensitivity at the crack tip area. A single edge notched bend specimen was used in the experiment and the result was compared to numerical analysis using the finite element software package ABAQUS TM. The comparison of the crack-tip principal and effective strains between the two alternate methods and finite element shows good agreement. Sensitivity at the crack tip area was higher compared to result from moiré interferometry with phase shifting. The two alternate methods were proven to be better than moiré interferometry with phase shifting alone.

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