A Photoplasticity Utilizing the Stress-Optic Law of Polyester at the R.P.E. Transition Temperature

Abstract

At the R.P.E. transition temperature, named by one of the authors, it was found that the stress-birefringence relation of polyester was linear even in inelastic range (in elastic range as well). By using this relation, factors of stress concentration and stress distributions at a free boundary were determined, and two-dimensional stress distributions at points apart from the free boundary were calculated by employment of the shear-difference method. Results obtained were in substantial agreement with the experimental results reported by M.M.Frocht. Moreover, the stress-strain relation of polyester at the R.P.E. transition temperature showed a good approximation to that of metal prototype, especially Al-alloy. Thus, it was proved that the photoplasticity utilizing the stress-optic law of polyester at the R.P.E. transition temperature is available to analyze the stress distributions in certain metals and polymeric materials.