yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

My vote for 2°).
The independancy of the "Visc" classes makes no sense. It is inherited
from very early ages of the code.

Raphael partly fixed the problem regarding kn vs. Young. You should talk
to him (I don't remember now why he did not make the inheritance Frict
-> ViscEl - to minimize the noise most probably).
There is now a choice to decide if kn should be translated like Young or
not (IIRC).
Your suggestion is to make it more transparent, the flag being set
depending on which attribute is defined. I like the idea.

Be carefull it must work with different syntax:
mat.young = ...
m=ViscElMat(.....,young=...)

B

On 16/12/13 08:56, François wrote:
> Hi everybody,
>
> I would like in my simulations to make possible the interaction
> between (Coh)FrictMat and ViscElMat spheres. I don't want to activate
> the cohesion so I would let CohFrictMat become FrictMat by
> inheritance. The idea is to study the granular flow of viscous grains
> with one of the boundary made of cohesive spheres who sticks together.
>
> I think there are two solutions : the first one seems easier because
> it just adds a new class, but the second one (which modifies a little
> the viscous classes logic) may deserves our consideration. The choice
> between one of them is the subject of my question.
>
> 1°) Create a new class : Ip2_FrictMat_ViscElMat_FrictPhys(). This
> functor would make an interaction physic just like
> Ip2_FrictMat_FrictMat_FrictPhys(), ignoring the viscosity and
> converting the young modulus of the frictional sphere to a stiffness.
>
> 2°) ViscElMat, unlike its name lets believe, doesn't inherit from
> ElastMat. The main reason I think is because a ViscElMat has
> stiffnesses {kn,ks} while an ElastMat has a young modulus and a
> poisson ratio {young,poisson}. FrictMat inherits from ElastMat, and
> the only additional attribute it has is the friction coefficient. As
> ViscElMat has a friction coefficient too, don't you think we could
> make ViscElMat a child of FrictMat ? To avoid breaking people's
> scripts, we can imagine that if the user sets {kn,ks}, those
> parameters will override {young,poisson} in the calculation of
> resulting contact stiffnesses. With this inheritance, and if the user
> sets at least {young,poisson} for both his FrictMat and ViscElMat, the
> contact will be possible between :
> - FrictMat + FrictMat => FrictPhys
> - ViscElMat + ViscElMat => ViscElPhys
> - FrictMat + ViscElMat(FrictMat by inheritance) => FrictPhys
>
> Can people working with/on visco-elasticity give their opinion ?
> (Anton, Raphaël ...)
>
> Thanks,
>
> François
>
>
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Bruno Chareyre
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ENSE³ - Grenoble INP
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