Temperature and time influence in the stress freezing of the epoxy Hysol 4290

Disks of the photoelastic epoxy known as Hysol 4290 have been subjected to constant load at various temperature levels and the birefringence has been recorded as time elapsed (creep test). Also disks of the same material were loaded at the critical temperature and then cooled, each to a different temperature level and, after they reached thermal equilibrium, the loading was removed while the temperature was maintained constant (recovery test). The effect of time on the fringe value is given for both groups of tests using the temperature as a parameter. Finally, tensile specimens have been subjected to various loads at the critical temperature and fringe response and failure recorded. The results obtained may be useful for the design of experiments and, in some cases, to shorten the time required to conduct a three-dimensional photoelasticity investigation using the “freezing” method.