Photoelastic stress patterns seen under polarised light, in a circular protractor. The plastic that the protractor is made from is displaying coloured interference fringe patterns. Areas of similar colour correspond to regions of similar stress. From these patterns, the direction and magnitude of the stresses can be calculated. This principle is used in photoelastic studies that use plastic scaled-down models to study stresses in real-life objects.
Model release not required. Property release not required.