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Re: Ip2_FrictMat_FrictMat_FrictPhys doc

 

Hi Jérôme,

Thanks for pointing out what was missing. I tried to fix in [1].

Even though we all here are at ease with these models, I think the "young questions" we still face (me, few days ago here) should demonstrate there is room for improvement... Hoping to avoid another https://www.mail-archive.com/yade-dev@xxxxxxxxxxxxxxxxxxx/msg03051.html,
That was an interesting discussion back in 2010. :)
Not sure this is what we want to avoid.
In general most of the confusion comes from the fact that FrictMat::Young is _not_ interpreted as a Young modulus by most (not all) functors, which some users do not realize - especially when documentation is overlooked. You could write ten pages of documentation to repeat that FrictMat::young is not a Young modulus for some functors, give all the possible equations, the confusion would still emerge from time to time due to the name.

I think the proposal below has the advantages to precisely give all expressions for the three relevant contact parameters, which I personally can not see for now in https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Ip2_FrictMat_FrictMat_FrictPhys (for any parameter).
I think it is now complete.

From your answers, I will obviously refrain from touching the general doc.
Touching is ok, erasing is not. ;)
I still see many things to improve/add in the sections we are speaking about.

And I'd propose a new version of Ip2_FrictMat_FrictMat_FrictPhys docstring keeping the physical explanations for the contact stiffness as
Problems of this new version:
- despite the above statement the explanations are still removed
- this new statement is wrong: "The $k_n,k_s$ expressions correspond to an harmonic average of particles compliances being proportionnal to $E_iD_i$" - in principle we try to cite the earliest source in science, yet the new version replaces a reference from 2009 by a reference from 2010.
- no need to mention "equivalent" diameter IMO
Then I committed on my side.

I think we all have slightly different ways to explain the same thing, so it is easier if one part of the doc is written by one person to keep homogeneity. Let me know if you still see problems or if you want to suggest additional content.

Cheers

Bruno

[1] https://github.com/yade/trunk/commit/0d04eb4cc9f2dbc27a738391f10234b74a8e73c1


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