How Can Photoelasticity Detect Minimal Stress in Window Glass?

[roy_lennon]

Hi,

I need to get the stress components on a window glass using photoelasticity technique.

How can I now the minimum amount of stress that can be detected using this technique?

Thanks!

 

[Studiot]

You presumably know how to use the technique?

The minimum amount is zero, usually free boundaries.

 

[roy_lennon]

Hello

Let me modify the question..

If I apply a force of 1 Newton to the glass, will the stress be detected using photoelasticity?
Or do I need to apply a bigger force so it can be detected?

 

[Studiot]

This is a 'how long is a piece of string?' question.

The basic method gives the difference between the max and min principle stresses at any point by counting the number (n) of fringes (dark/ light transitions) from a point of known stress difference - hence my comment about free edges. there is, of course a material fiddle factor (f) you can juggle witht he thichness (t) to get any value you require.

$${\sigma _{\max }} - {\sigma _{\min }} = \frac{{nf}}{t}$$