1. Photoelasticity is the property of certain materials to exhibit changes in optical properties when under mechanical stress.

光弹性是一些材料在受到机械应力时，在光学性质上出现变化的特性。

2. The photoelastic technique is often used in engineering to study stress distribution in components.

光弹性技术常被用于工程领域，以研究零部件的应力分布情况。