Simple Casting and Testing of Optical and Mechanical Properties of Domestic-Grade Resins: A Case Study of Their Use as Photoelastic Materials

Abstract

(Transmission) photoelasticity – an experiment-based stress analysis – needs specimens made of transparent birefringent materials, e.g., epoxy resin and polycarbonate. Typically, these materials are imported from abroad. Due to their considerable price, use of domestic-grade resins, then, is of practical interest to ease student learning and photoelastic experiments or research. With these goals keeping in mind, this paper presents the results of optical and mechanical investigation on photoelastic parameters using specimens made of two different resins: 024-A and Araldite M-1 (stereolithographic-resin). Resin casting process was that of a simple route. Tests were mechanically and optically carried out on simple specimens
cut out of the cast resin plates in the shape of a dog-bone (type 3 of ASTM D638) and a circular disk under diametral compression in order to evaluate their Young’s modulus and to calibrate the photoelastic constants – material stress fringe value and figure of merit. The results obtained, especially the material stress fringe value, are comparable to those of polycarbonate and Homolite 911 (materials typically used in photoelasticity), allowing the use of the domestic-grade resins as photoelastic materials.