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Methods to make photoelastic samples
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Most of the transparent material around you have photoelastic properties. However for most of them you would need to load them so strongly to observe a photoelastic signal that you cannot really use it as photoelastic material. Another reason not to use any random transparent material to make a photoelastic sample is that most of the time no special attention have been paid while forming the material so that it is full of residual stresses and not really usable. As an example here is a pair of glasses:
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Most of the transparent material around us have photoelastic properties. However for most of them we would need to load them so strongly to observe a photoelastic signal that we cannot really use it as photoelastic material. Another reason not to use any random transparent material to make a photoelastic sample is that most of the time no special attention have been paid while forming the material so that it is full of residual stresses and not really usable. As an example here is a pair of glasses:
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![IMG_0407](uploads/254a0670b5a0f6c15db9476fca0cfb7a/IMG_0407.JPG)
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So making a photoelastic sample is not simple. First you have to choose your material so that its photoelastic ability is enough to observe something significant in the range of stresses you want to apply. Second you have to make your sample without trapping any residual stress in it.
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That is why making a photoelastic sample is not simple. First of all, it is necessary to choose the material you will use as a function of:
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* the load you want to applied,
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* the shape of the sample you want to get,
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* How many sample you need,
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* what you expect to measure and
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* the money you have.
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This different criteria have to be carefully considered before choosing how you will make your photoelastic sample among the different methods presented below. The section below will guide you to make samples from just just using a piece of gel to casting polyurethane or cutting photoelastic pads. So first, you have to choose your material so that its photoelastic ability is enough to observe something significant in the range of stresses you want to apply. Second you have to make your sample without trapping any residual stress in it. Let's see it more carefully
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Cutting samples out of a sheet
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The first method consist in cutting the sample out of a sheet of photoelastic material. You pick the right material and cut it using different methods listed in [this tutorial](https://git-xen.lmgc.univ-montp2.fr/PhotoElasticity/Main/wikis/cutting-sample)
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The first historical method consists in cutting the sample out of a sheet of photoelastic material. You pick the right material and cut it using different methods listed in [this tutorial](https://git-xen.lmgc.univ-montp2.fr/PhotoElasticity/Main/wikis/cutting-sample)
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Molding urethane samples
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