I want to estimate Young's modulus of PAA gel by measuring the stress and strain by the uniaxial compression test of a cylinder-shaped material.
But I don't know anything about material science, so I'd like to get some advice before experimenting.
Below is my experiment method.
1. Sample preparation: PAA gel cast in a cylindrical shape with 4.7ml diameter (ID of 1ml syringe), 10ml height (aspect ratio: ~2.1)
2. stress applying method: vertical loading of weight by using gravity; Incremental loading of SUS metal beads(0.266g each) on top of the plastic linear guide(as preload, 2.0g), load(weight*g) is then divided by the top area of the cylinder(pi*(4.7/2)^2) to estimate stress.
For example, load the sample first, put a linear guide on top of the sample, and gradually increase the load : [0, 2.0, 2+0.266, 2+0.532...] until the nominal strain reaches 0.2.
3. strain measurement method: local pattern matching using crosscorrelation or phase information of the image (which is already familiar to me, fortunately)
during the pre-experiment, I accidentally set the aspect ratio to 1:1, and the estimated modulus came out 2-3 times higher than the nominal value.
I'm looking forward to your advice on what might be the potential problem, except for the aspect ratio.
Any kind of advice will be appreciated.
thank you.
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