← Back to team overview

yade-users team mailing list archive

Re: the relationship of poisson ratio and tangential stiffness


> I have checked the relationship of the physical parameters and the
> required parameters in Yade. I am confused how to get the shear
> stiffness (tangential stiffness) from the poisson ratio and normal
> stiffness correctly. You know, according to the description in
> Vaclav's thesis page 52. I get the poisson ratio is not equal to the
> Kt/Kn (shear stiffness/normal stiffness) directly. However, in
> Ip2_2xCohFrictMat_CohFrictPhys, the shear stiffness is calculated just
> from Kn*poisson ratio. You know, in PFC theory, the users always need
> to give the shear stiffness directly.  I know the poisson ratio (v)
> depends on the dimensionless ratio Kn/Kt. But I don't know how to get
> this formula (v=Kt/Kn). How to decide the coefficient?


the way to compute Kn/Kt depends on the Ip2 functor in use.

In the case of the Cpm model which you refer to (page 52), I was
directly specifying the Kn/Kt ratio in the CpmMat class (I call it
G_over_E, but G/Kt=E/Kn), the ElastMat::poisson is not used at all.

Admittedly, the ElastMat::poisson is quite confusing, maybe replacing it
by the kt/kn ratio (ktDivKn) would be better. I think it is there for
historical reasons, though other people might know better.

Cheers, v