Experimental Mechanics @ Michigan State University
		EM Basics: Reflection Photoelasticity
A compressor blade with photoelastic coating (from SNECMA)				Fringe pattern around a crack taken from a reflection photoelastic specimen.
It is possible to apply a reflection coating to a real engineering component and to bond to this coating a thin sheet of photoelastic material. When the component is loaded the surface strain in the component is transmitted into the photoelastic sheet generating stress in it. The resulting fringe patterns can be observed by illuminating the component with polarised light and viewing it through a polariser. This technique allows the stresses in a component to be fund directly. It avoids the need to scale stresses from models to real components which is necessary in two- and three- dimensional photoelasticity. The major disadvantage of the technique is that only surface stress data can be obtained.
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