yade-dev team mailing list archive

[Chiara Modenese <c.modenese@xxxxxxxxx>]

On 13 December 2011 10:35, Klaus Thoeni <klaus.thoeni@xxxxxxxxx> wrote:

> Everyone on holidays already?
>
> Well I am still wondering why for the calculation of the stiffness of a
> sphere
> and a facet the radius of the facet is assumed to be twice the radius of
> the
> sphere.

I can say that this is what is generally assumed in the current literature
but I cannot say more as I wonder is only an assumption.
Chiara



> This is basically the value comming from GenericSpheresContact. In my
> opinion it doesn't make sense. The facet can be seen as a sphere with
> radius
> infinity. So if we take the harmonic average (as it is done in
> Ip2_FrictMat_FrictMat_FrictPhys ) considering e.g. rb->infinity the
> stiffnesses
> become kn = 2*Ea*ra and ks = 2*Ea*ra*Va.
>
> You agree? If so I could commit the changed code. Please let me know.
>
> On Sun, 11 Dec 2011 06:38:35 PM Klaus Thoeni wrote:
> > Hi Guys,
> >
> > what value for refR does the GenericSpheresContact return for a facet? By
> > introducing TRVAR2( Ra, Rb ) e.g. in Ip2_FrictMat_FrictMat_FrictPhys::go
> it
> > seems if a sphere is intersecting with a facet the refR value for the
> facet
> > is just 2*refR of the sphere. Is this true? And when yes, what's the
> > reason? It's fundamental for kn and ks, isn't it?
> >
> > Thanks,
> >
> > Klaus
> >
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