Time- and temperature-dependent stress-strain analysis using white-light photoviscoelasticity

In the current photoviscoelastic techniques, a set of multiple data, at least two images under plane polarization at a single instant, are necessary to determine not only fringe order but also principal birefringence direction simultaneously over the whole field of specimen. Therefore, the current techniques cannot be applied to such problems in which the good repetition and reproducibility of experiments are not expected. In order to overcome this type of difficulties in the analysis of time dependent phenomena, the authors proposed a photoelastic method using a white incident light with a set of the three primary colors. When using this method, not only fringe order but principal birefringence direction are successfully and easily determined from a single colored image. Utilizing this method together with photoviscoelastic constitutive equations, time dependent principal stress and strain difference, also their directions are successfully obtained. In this paper, the fundamentals of the white light photoviscoelasticity are described briefly, then a successful application of the method to the analysis of an example of viscoelastic problem is shown. An example problem of a viscoelastic strip having a hole under tension at several temperatures, at which the material shows remarkable viscoelastic behavior, is successfully analyzed.