yade-users team mailing list archive

["Hadda Nejib" <nejib.hadda@xxxxxxxxxxx>]

Hi,



You're right Chiara, it works for the last version.


I have some other remarks:

1- Yade uses 3 entities to define the contact normal, "normal", "prevNormal" and "currentNormal". in what does currentNormal differ from "normal". 
I think also that "prevNormal" is overwritten by "normal" or inversely when displaying them because there is no differences between the 2 vectors (you can see that in an .xml file for example). so if it is the case I think we should fix it.

2- While computing the shear increment extracting these componnents (vel,angVel,contactpoint,Pos1,Pos2,normal, O.dt), computing vectors c1x and c2x as follow

c1x= ContactPoint-pos1
c2x= ContactPoint-pos2


and using this code (Same one used in ScGeom) :


relVel=vel2+(angVel2).cross(c2x)-(vel1+(angVel1).cross(c1x))		

delta_un=(relVel*normal)*O.dt

shearVel=relVel-(relVel*normal)*normal

ShearInc=shearVel*O.dt


I found that ShearInc computed as above differs from the ShearInc given by Yade bzr (Last version). Is there any projection, or operation on coordinate local/global systems left for me to do so that I find the same value as Yade.

Many thanks !











-------- Message d'origine--------
De: yade-users-bounces+nejib.hadda=cemagref.fr@xxxxxxxxxxxxxxxxxxx de la part de chiara modenese
Date: lun. 16/08/2010 15:28
À: yade-users@xxxxxxxxxxxxxxxxxxx
Objet : Re: [Yade-users] relative normal and shear displacements andrelative rotations
 
Hi Nejib,

sorry for long delay in replying.

>
> 'shearIncrement' seems not to be an attribute to the object 'ScGeom', Do
> you agree ? is there any alternative to call directly otherwise?
>
May I guess what release are you using? In last release shearIncrement is
accessible via python in read-only mode (see line 54 of ScGeom.hpp) which
overrides shearInc private attribute of ScGeom (updated into precompute
function, line 35 of ScGeom.cpp).

cheers, Chiara