yade-users team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

On the same line : the energy dissipated by Cundall's damping in 
quasi-satic conditions is negligeable. You find that the work input from 
boundaries equals more or less plastic+elastic work at contacts (tests 
with pfc3D, damping~0.2, frictional contacts, ~50k iterations in a 
triaxial test). It corresponds with the fact that Cundall's damping 
looks useless in _some_ quasi-static conditions, after Yade simulations 
and discussions with Gaël, Vincent, and Vaclav.

|Δε|*|σ| sounds straightforward, but with du and df, and non-linear elasticty on both normal and shear, and plasticity for fun, I have no initial guess... Computing the energy dissipated in Law2_ScGeom_FrictPhys_basic is straightforward, for sure.
On the top of that, there is the case when plasticity==true at time "t", and plasticity==false at time "t+dt". You have to decompose |Δε| into plastic and elastic on one timestep. Straightforward again with the *_basic law, but with Hertz? I have no clue yet.



Bruno

Václav Šmilauer a écrit :
> > Put a "Real plasticWork" in the functor. Compute the energy dissipated 
> > at one contact on time increment dt, and include  a "plasticWork+= ..." 
> > in the if(plasticityCondition) bracket of the functor.
> > Don't ask me how to define plastic work at contact with an 
> > elasto-plastic Hertz-based law... ;)
> >     
>
> I think since the formulation is incremental, you can use |Δε|*|σ| for
> energy dissipated in plastic slip by Δε at plastic stress σ...?
>
> Generally, there is no unified function for dissipation. You could,
> though, sum kinetic energy of particles, potential energy (if there is
> some potential field), and subtract cummulative external work (boundary
> conditions). That should give you pretty good image of system energy
> evolution, including damping, plasticity and dissipation by numerical
> entropy ;-)
>
> Cheers, v.
>
>
>
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