yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxxxxxx>]

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