yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

> You're right! Some people consider granular matter as a continuous media. I don't.
>
The integral is for one grain alone. Considering one grain as a
continuum doesn't sound so absurd, does it?
We are far above the atomic scale.
> The particles are rigid, i.e. 6 independent DOFs and that's all (Elasticity is introduced in force-laws).
> We can always define whatever we want. The question is what is the sense of our definition.
> As I said, the definition of a particle stress is ok, but the volume used in this definition is a matter of convenience.
I don't really trust the "rigid particle" story. A contact point being a
point, it can't be deformed, then it must be the particle that is
deformable. Real silicate grains are deformable too.
> Yade users must form their own opinions
Thats true.
>  and given them a function that compute a particle stress is in my opinion a bit dangerous.
It is not dangerous as long as people consider a number for what it is.
The documentation says "exact mean stress from contour integral of
external load". The demonstration starts with "at equilibrium", and the
whole thing is classical elasticity. Fair enough.
> Why don't you provide a function to compute the moment tensor and then the user is free to use the volume he want in order to compute the stress?
Simply because I never heard about moment tensor. Not saying it would
not be interesting to add a function for that.
> The real aim of this proposition is to empower the user, who sometime use a function as a black box.
Mmh... Who is to blame in that case? And, come on, those ones would
remember they have to divide the return value by a volume?!


Bruno