Novel Photoelastic Approach in Analysis of Elliptical Holes in Thick Plates

Abstract

Nondestructive photoelastic stress analysis of elliptical holes in thick plates was carried out. Using Plexiglas as a model material, the scattered photoelastic technique was used. In a novel approach, the residing birefringence in unstressed commercially available polymer plates was introduced as an information carrier. Pairs of monochromatic coplanar rays of polarized light were sent, in two perpendicular directions. The experimental data captured from each pair, for points at the load‐free boundaries of the holes, were combined to achieve a complete determination of the stress state at the point of a pair's intersection. The nondestructive technique used allows optical scanning of stresses through the thickness. The photoelastic data obtained was utilized in determining stress‐concentration factors at the ends of the major and minor axes of the elliptical holes. The experimentally obtained distributions of the stress concentration through the thickness were compared with those cited in the literature. The introduced photoelastic approach along with the material array of equidistant parallel lines proved to work efficiently. Moreover, it has been shown that Plexiglas can be employed, in spite of its low stress‐optic coefficient, as a quasi‐sensitive photoelastic material.