Fringe multiplication and thickness effects in birefringent coating

The feasibility of applying fringe-multiplication technique in birefringent-coating analysis is studied, and the conditions under which this technique can be used are discussed. The fringe-multiplication technique is then applied to birefringent-coating analysis of a plate with a central circular hole under uniaxial tension. The experimental results are then compared with Howland's analytical results for the shear-stress distribution along the minimum cross section and for normal stress distribution along the edge of the plate. Duffy's correction factors for curvatures and strain gradients are used to estimate the correction in the latter experimental results.