A transparent photoelastic polymer containing a single hole of $$500\mu m$$ is loaded under tensile stress. The same experiment is done again using Digital Image Correlation (DIC) as an analysis method this time. The contour plot shown in the DIC experiment are percentiles of $$\epsilon_1$$ - $$\epsilon_2$$, where $$\epsilon_{1}$$ is the deformation in the first principal direction and $$\epsilon_2$$ the deformation in the second principal direction. The number of photoelastic fringes passing through a material point on the specimen’s surface is also proportional to $$\epsilon_1- \epsilon_2$$, allowing a qualitative comparison of both methods by looking at:

• The fringes concentration
• The number of fringes passing through a single material point and their direciton

This video compares both methods.

Both specimens’ dimensions were chosen according to the ASTM D632 Type V. Test speed: $$0.1mm/min$$

It is possible to see that the photoelastic specimen firstly reveals large fringes going through the whole specimen from left to right, that is probably because the specimen is experimenting torsion, due to the fact it was not perfectly straight between the grips. Once the whole specimen emits an almost uniform color (second 40), 6 petal fringes (circular) are cricling the hole.

Experiments done in collaboration with Rolland Delorme, at Ecole Polytechnique Montreal during November 2015.

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