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[Bruno Chareyre <question225776@xxxxxxxxxxxxxxxxxxxxx>]

Question #225776 on Yade changed:
https://answers.launchpad.net/yade/+question/225776

    Status: Open => Answered

Bruno Chareyre proposed the following answer:
>As I said before, I dont know the reason why the minimal value of
friction is used.

The hardness of the contact between talc and diamond is the hardness of talc. The logic is the same in our case for friction.  
Would you suggest a better default behavior?
Since it is only a default it is not really important anyway. The good question is what physics you want to simulate, and this really depends on your materials, not on Yade. We can't decide for you.

>It would make sense if the value of friction (frictionAngle) is used
for checking plasticity condition only in Yade.

I don't understand this statement.

>Could you please give a brief summary of your PFC problem and your
solution?

2 groups of spheres (say A and B), 3 values of contact stiffness to be defined independently for A-A, A-B, and B-B.
Not possible if stiffness is assigned to materials A and B (3 equations, 2 unknowns...), which is the case in PFC and in YADE.
For PFC, there was simply no solution at that time. For Yade, there is now the matchmakers. They were introduced by Vaclav in response to a question very similar to yours. I don't know if they have been really used by somebody yet.

>Yes, this can be a great solution, providing that the dummy friction of
b1 is used for that purpose only. I'm not sure about that

You can be sure. I wrote CundallStrack, and I know Hertz is using the
same logic.

>What about this idea:

Are you speaking of experiments setup or simulation? If this is a
simulation, this would be a sort of debugging, and I can tell you that
you will find the expected result: fmax = weigth*tan(min(f1,f2)).

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