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[Bruno Chareyre <question446267@xxxxxxxxxxxxxxxxxxxxx>]

Question #446267 on Yade changed:
https://answers.launchpad.net/yade/+question/446267

    Status: Open => Answered

Bruno Chareyre proposed the following answer:
Hi Tijan,
I would think 1) is as expected. When adhesion disappears there is still frictional resistance, the elastic force in excess wrt the maximum frictional force is counted as part of frictional dissipation (in the same step when the bond is broken).
It should be substracted from bond breaking energy probably, to not count it twice.

2) is more a problem. The mismatch comes from the fact that the elastic potential is not exactly the sum of
normEnergy[i] = 0.5*(i.phys.normalForce.squaredNorm()/i.phys.kn)
shearEnergy[i] = 0.5*(i.phys.shearForce.squaredNorm()/i.phys.ks)

There is coupling term combining the normal and shear components, which is small as long as the normal displacement is small compared to diameter, but which is there. This is what you see (since un is non zero and changing during your scenario). 
So I would say: the energy is conserved (*), but the internal energy you are plotting is only an approximation of the exact one.
(*) And you can check that by integrating the external work along complex paths and find it path independant (without bond breakage). I happen to have a paper in preparation about this, I can send it to you later.

Bruno

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