Photoelastic stress patterns of a protractor, viewed using polarised light. The plastic 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 stresses placed on th eprotractor can be calculated. During photoelastic studies, these calculations can be related to stresses in real designs by using plastic, scaled-down models.
Model release not required. Property release not required.