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[Jan Stránský <question270336@xxxxxxxxxxxxxxxxxxxxx>]

Question #270336 on Yade changed:
https://answers.launchpad.net/yade/+question/270336

Jan Stránský proposed the following answer:
Hi Jabrane,


> In fact i try to calculate the energy balance based on energy calculation
> in UDEC.
> The formulas used were taken from Energy Calculation in UDEC 5 for each
> gridpoint.
>

I don't work with UDEC, but in general you have:
- kinetic energy (easy to compute)
- potential energy (of various forms, e.g. elastic). In your case
NewtonIntegrator has zero gravity and also from physical point of view
gravity potential energy makes no sense
- dissipation, a tricky part - dissipation by friction, by contact law
damping, by NewtonIntegrator damping, by contact law dissipation (e.g.
contact breakage)...........
- adding new energy to the system if you have interacting body with
prescribed velocity (the piston in your case)

some of the energies might be negligible (like kinetic energy in
quasi-static simulation), you can try purely elastic simulation comparing
added energy by piston and elastic energy. If they equal in elastic case,
then probably you could compute dissipation as the difference between added
and elastic energy.


>
> "Don't you want potential energy of elastic deformation instead?"
> I think you are right but the question is how can i calculate the
> potential energy of elastic deformation without the formula of UDEC5's
> manual ?
> There is a tool in Yade with which we can calculate it ?
>

there are more options:
1) calculate it manually:
   E_interaction = 0.5*stiffness*displacement^2 = 0.5*force^2/stiffness #
force = stiffness*displacement
   E_total = sum(E_interaction for all interactions)
2) some laws implements elasticEnergy() function, e.g. [1]

cheers
Jan

[1]
https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Law2_ScGeom_FrictPhys_CundallStrack.elasticEnergy

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