In a photoelastic experiment, it is necessary to know the material stress fringe constant of the photoelastic specimen to determine the stresses from the measured isochromatic fringe orders. This type of compensator was proposed by the previous researchers. The recent image processing development of the stress pattern provide a means for making convenient compensator. The material stress fringe constant is determined using the distributions of isochromatic fringes in the wedge shaped plate under tensile load. The stress fringe constant measured with this method is applied to obtain the stress distribution along the central line on the tapered shank of the wedge-shaped plate. Photoelastic results using the measured material fringe constant are compared with FEM analysis. Two results are comparable, so it can be seen for the measured material fringe constant to be valid.

Many polymers exhibits sufficient birefringence to be used as photoelastic specimen material. Common polymers as polymethylmethacrylate (PMMA) are often used as photoelastic specimen. In a photoelastic experiment, it is necessary to know the material fringe constant of the photoelastic specimen to determine the stresses from the measured isochromatic fringe orders. The material stress fringe constant is determined using the simple tension specimen. The stress fringe constant measured with this method is applied to obtain the stress distribution in a tensile plate with a circular hole. Photoelastic results using the measured material fringe constant are compared with FEM analysis. Two results are comparable, so it can be seen for the measured material fringe constant to be valid.