What is "photoelasticity"

n. a technique for studying and measuring the stresses and strains in an object by means of mechanical birefringence

Photoelasticity is a method to determine the stress distribution in a material experimentally. The method is mostly used in cases where mathematical methods become quite cumbersome. Unlike the analytical methods of stress determination, photoelasticity gives a fairly accurate picture of stress distribution around discontinuities in materials. The method is an important tool for determining critical stress points in a material, and is used for determining stress concentration in irregular geometries.