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[loiseaurare <question631624@xxxxxxxxxxxxxxxxxxxxx>]

Question #631624 on Yade changed:
https://answers.launchpad.net/yade/+question/631624

    Status: Open => Answered

loiseaurare proposed the following answer:
Hi Xavier,

I am also working on the modelling of breakage of rock, and have been
investigating that question for a bit of time.

I have found that CohFrictMat and JCFpmMat are quite similar, meaning they have the same expression of contact stiffnesses, however JCFpmMat has a few built in functions that come in handy :
the "equilibrium distance" is automatically set when creating a pack of spheres, while for the moment you still have to set it manually when you write a script using CohFrict Mat, although I think someone might be implementing that precise feature.

With JCFpmMat the number of shear-broken or tensile broken bonds is
tracked automatically, so that's quite cool as well, because you can
easily track bond failure. Don't think such a function is implemented in
CohFrictMat.

However it is not clear to me how you handle plastic behavior with
JCFpm, while it is a bit more clearer with CohFrictMat.

Oh, and in JCFpm you can introduce weak planes, that could represent
foliated plans in a rock for example, depends which kind of rock you
want to model, but it seems like a good way to introduce macro-scale
defect, and maybe microscale.


CpmMat is a bit different, because it was designed for concrete material. The parameters used to describe the model are eps and sigma limit, whereas in the two other models you work with shearCohesion and tensileCohesion In the examples on CPMMat you can find a uniaxial test on a sample that is a good starting point for some calibration model.

As far as I know, none of those contact law include viscous damping
though....

Hope that was of any help,
Cheers

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