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[Bruno Chareyre <question234129@xxxxxxxxxxxxxxxxxxxxx>]

Question #234129 on Yade changed:
https://answers.launchpad.net/yade/+question/234129

    Status: Open => Answered

Bruno Chareyre proposed the following answer:
Hi Lingran,

Even before considering plastic dissipation, do you get a correct energy balance when friction=0 (no dissipation)? 
I guess you don't. The reason is twofold.

(1) the global energy tracking is present in Law2_ScGeom_FrictPhys_CundallStrack but not in Law2_ScGeom6D_CohFrictPhys_CohesionMoment (*). Since you are combining them, you see something in O.energy['elastPotential'] but it only partly reflects the total elastic energy.
You can get elastic energy independently for each contact type with lawN.normElastEnergy() and lawN.shearElastEnergy() (where N will be 1 and 2 in your script).

(2) you are using contact moments, and unfortunately there is no
law2.bendingElastEnergy(). So this energy is simply missing in the
total, even after considering (1) above. You may write this function in
c++ actually, it would be useful for everyone. It is not very difficult
using the example of normElastEnergy(). Let us know.

Bruno


(*) It was my decision to not track elastic energy since, unlike plastic dissipation, elastic energy does not have to be incremented at each step. Computing it all the time was significantly slowing down the simulations for no good.

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