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How to calibrate the magnitude of local stress field in 2D specimen

Asked by Wang Benxin

I am simulating the uniaxial compression of rock specimen in 2D using spheres. However the bonding parameters such as cohesion and tensile strength are in the magnitude about 1e10 Pa which is too high if I want to get a macro stress-strain curve and UCS with the unit or magnitude MPa like the experimental tests. The local stress field is also in the magnitude 1e10 Pa for the solving result. But the magnitude of stress field in the experimental uniaxial compression is 1e6 Pa. Hence, my question is that how o calibrate the local stress magnitude as the experiment in the numerical model.

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Robert Caulk (rcaulk) said : 		#1

Hello,

>>However the bonding parameters such as cohesion and tensile strength are in the magnitude about 1e10 Pa which is too high if I want to get a macro stress-strain curve and UCS with the unit or magnitude MPa like the experimental tests.

Why do you presume that the micro-parameters should be of the same order of magnitude as the macro-parameters?

Have you considered increasing the interaction range to simulate grain interlocking better? [1]

Cheers,

Robert

[1]https://www.sciencedirect.com/science/article/abs/pii/S0022509612002268

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Wang Benxin (yushujinshan) said : 		#2

Hi Robert,

>>Why do you presume that the micro-parameters should be of the same order of magnitude as the macro-parameters?

I got the local stress field in experiment. Hence, I want to make the comparison and verification of local stress field between simulation and experiment.

>>Have you considered increasing the interaction range to simulate grain interlocking better? [1]

Yes, I had increased the interaction range as the paper saying.

Thanks,
Benxin

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Robert Caulk (rcaulk) said : 		#3

I guess this question depends entirely on how you are estimating the local stress field. Please indicate this information if you wish to receive accurate assistance.

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Wang Benxin (yushujinshan) said : 		#4

Hi Robert,

In experiment the stress field was calculated base on the damage evolution constitutive equation. And it's magnitude is 1e6 Pa. The numerical test uses the Law2_ScGeom_JCFpmPhys_JointedCohesiveFrictionalPM. And the local stress in numerical model is exported by VTK and showed in ParaView.

Can you help with this problem?

Provide an answer of your own, or ask Wang Benxin for more information if necessary.

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