A Study of Stress Analysis for a Residual Stress Model by Digital Photoelasticity

The stress analysis for a model with initial stresses, which we term a residual stress model, is performed by digital photoelasticity. The stresses applied on the residual stress model are obtained by analyzing both the initial stresses and the resultant stresses. The method used for analyzing the stresses applies the principle of superposition of the stress to photoelasticity. which is a well-known technique in the field of elasticity. In the digital photoelasticity technique used, the principal stress direction psi and the relative phase retardation rho are analyzed by photoelastic techniques using linearly polarized light. This technique overcomes the phase difference error associated with a quarter-wave plate by employing incident light at three different wavelengths, and using an unwrapping technique that allows psi and rho to be determined using the arctangent function. A residual stress model produced by a disk containing frozen stresses that was subjected to a diametral compressive load at an angle of 31 degrees was used to experimentally test this method. The values of the stresses of the loaded disk model analyzed were in good agreement with corre- sponding theoretical values at all locations far from the loading points of the residual stress model.