Title: Clamp down on stress

Aongus McCarthy

School of EPS

Certain transparent materials reveal colourful contour patterns when they are placed under mechanical stress and viewed between crossed polarisers. The patterns are visible because of the induced birefringence which is proportional to the applied stress. This is known as mechanical birefringence or photo elasticity, and was first described by the Scottish physicist Sir David Brewster in the early 19th century.