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cb-geo / mpm

CB-Geo High-Performance Material Point Method
https://www.cb-geo.com/research/mpm
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[Materials] MohrCoulomb derivatives of R #597

Closed ezrayst closed 4 years ago

ezrayst commented 4 years ago

Not sure about the derivatives highlighted in this PR.

If @tianchiTJ is OK, I would make the test cases too. Below is my document on the derivatives.

image

tianchiTJ commented 4 years ago

I think there should be a negative sign in A.42, and others should be good in my opinion.

ezrayst commented 4 years ago

That is another thing we need to discuss. I use sin convention for Lode Angle and that's why there is no negative. But you agree in the pull request? I will make the test cases then

tianchiTJ commented 4 years ago

You equations are right, but the rho=sqrt(2J2), so I think the original code should be correct

ezrayst commented 4 years ago

I see. Understood thanks!