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Re: The convergence criterion in YADE


so CC is used to determine whether the calculations can be stopped,
because nothing is moving, right?

Yes/No, see below.

so you mean that we need to calculate a sum of all Forces in
PhysicalActionContainer, and also calculate their mean value.
And momentum is ignored?

CC is just an heuristic approach to evaluate stability. Momentum could equally well be included in the formulae, but in the most common definition of CC they are not.

But then - if it determines that the simulation is
finished=stable=all_forces_are_in_equilibrum - then I guess that we want
to simulation to be automatically stopped :).

Not always! For instance, if you want to simulate a quasi-static triaxial test, you assign a final value of axial strain, not CC. But you can record CC during the test to check that it is always "very small", i.e. not far from static conditions. However I don't know exactly what "very small" means ;). In fact, I am not very confident when someone try to proove quasistaticity based on CC only...
So, perhaps we need a standalone engine to record CC AND a simulation stopper based on this engine.

Chareyre Bruno
     Maître de conférence
     Institut National Polytechnique de Grenoble
     Tél :
________________________________________ bureau I 08 Laboratoire 3S (Soils Solids Structures) BP 53 - 38041, Grenoble cedex 9 - France _______________