yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

Václav Šmilauer a écrit :
> > You can repeat the test, is simple. The fact that the shear force
> > changes sign from one case to the other, is not correct. The shear
> > force is dependent on the relative shear velocity that in turn depends
> > on the ids at contact as we define them. To me this happens because we
> > do not define a local system. 
> >
> > Please correct me if you see I am wrong or please explain me why the
> > shear force changes sign (if it was really a global system as was
> > already pointed out, it should not happen).
> >     
>
> Hi Chiara, if I understand right, shearForce get negated if you swap
> ids. That is consistent. shearForce is in global coordinates, but to one
> body (id1*), it applies positive (action), while to the other body
> (id2*) negated (reaction). 
>
> Does this explain what you describe?
>   

Or did you force the swap in a non-symmetric case, which could really 
result in a wrong sign (not sure)?
It would be a user defined problem, since such swap would never happen 
by default.

B