Hole-in Plate: Photo-elasticity

The purpose of this lab is to teach students about stress, strain, and the internal stress distribution of a plate which has a hole cut into it.

In later labs they will use quantitative data and maths to analyse this topic in detail, but this first lab is introductory.

A perspex plate with 'birefringent' properties is used, along with polarised light, to give a visualisation of the stresses.

Students can study the 'fringes' (colour patterns) to determine the way the stresses are moving through the plate.

Students simply add weights to the apparatus and study the result, observing the 'shape' formed by the stresses in the plate.

It is therefore very low stress, enjoyable and education for the students.