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Re: Poisson


that kn influence the macro parameter E of the sample, but that there is also a relationship between alpha=ks/kn and nu (macro). Probably I am interpreting something in the wrong way. Could you clarify me on this point, please? Is there a dependence somehow?

Thanks a lot.


Hi, I don't really understand your question... explanation given by Bruno and your citation from the paper are not antagonistic:

kn mostly influence the macroscopic Young modulus,
and the ratio ks/kn mostly influence the Poisson's ratio.


Indeed, we are all saying the same thing.
There is a strong property : Poisson's ratio is influenced ONLY by ks/kn (also by porosity, size distribution, etc, but not by other parameters of the contact law : E and friction).

However, proving that a relationship exists is one thing, giving the exact relationship is something else. There are many papers showing the dependance, or deriving approximate relations in particular cases, but I don't know one giving nu as a function of {ks/kn, porosity, PSD, fabric,[put whatever comes to mind]}. Even worst, packing properties are anisotropic as soon as the loading is not pure isotropic compression, so that we should not speak of "nu", but nu_xy, nu_xz, etc.