yade-dev team mailing list archive

[Chiara Modenese <c.modenese@xxxxxxxxx>]

On 14 January 2011 07:55, Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx> wrote:

>
>    - Add incremental formulation for the moment rotation (bending only) to HM law (it is very similar to the code for the shear part as written in ScGeom - it has been tested but feedbacks are welcome).
>   PS Let me know if you are interested to have it also in "Law2_ScGeom6D_CohFrictPhys_CohesionMoment" where actually the total formulation is already present.
>   @Bruno: maybe in ScGeom we could add this incremental formulation too?
>
>
> Hi Chiara,
>
> Good job!
> Could you validate this in beam flexion or other things?
>
I compared with quaternions (for elastic behaviour) and I got the same
result. Moreover, the problem of rotations bigger than 180 deg would be
solved with the incremental formulation (that is why I prefer it, it is also
easier to understand than quaternions, @Vaclav: one day I will see them :-)
). I will try to do a more quantitative comparison using a beam like
behaviour (is it theoretically possible, btw?).


> Yes, it would be interesting to add relAngVel in ScGeom and incremental
> code in CM law.
>
Ok, I will do it and let you know for approval before commit. I know you do
not want to add too much in there but this time would only be a matter of
few lines of code and I think it could be useful for other people using
linear laws or such.

>
> About Plassiard's rolling : using relAngVel is not exactly equivalent to
> the equations you found in this paper. You are computing bending, while
> Plassiard tried to isolate "rolling". The difference is not big, and I can't
> personaly states that one or the other is better. They should give very
> similar results, I'm sure.
>
Yes, I realized it is not the same that is why I asked about it. Anyway I
coded in both ways (the Plassiard's formulation is in the code as well but
for now is commented out since I did not really tested it).

Ciao, Chiara

>
> Bruno
>
>
>
>  modified:
>   pkg/dem/HertzMindlin.cpp
>   pkg/dem/HertzMindlin.hpp
>
>
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> --
> _______________
> Bruno Chareyre
> Associate Professor
> ENSE³ - Grenoble INP
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