Hybrid stress analysis of perforated tensile plates using multiplied and sharpened photoelastic data and complex-variable techniques

An experimental study is presented on the effects of varying the number of terms in a power-series representation of the stress function relative to determining the stresses around a circular hole or an elliptical hole in a finite-width, tensile loaded plate. Photoelastic data are hybridized with complex variable/mapping techniques to calculate the tangential stress on the boundary of the cutout. Accuracy/reliability is enhanced by twice-multiplying and sharpening the measured isochromatics using digital image processing. Actual and calculated fringes are compared qualitatively. For quantitative comparison, percentage errors and standard deviations of the percent age errors are calculated for all measured input data by varying the number of terms in the stress function. The hybrid results agree within three percent with those predicted by theory and finite-element analyses.