yade-users team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

> (16) is supposed to update shear force F_s (vector):
>
> 	F_s=F_s+K_s*ΔX_s
>
> but this is not correct, since you add ΔX_s (which is in the _current_
> contact plane) to F_s (which is shear force from the previous step, i.e.
> in the _previous_ contact plane)!!
I don't understand the problem. F_s and ΔX_s  are in the global 
coordinate system, not in any contact plane.

>  Not a single word about transforming
> F_s to the current plane first, which must be done and really happens in
> yade code [2].
>
>   
Rotating the previous force to account for the rotation of the pair and 
computing the new force increment are two independant things.
There is no constitutive behaviour in a simple rigid-body rotation, so 
it is correct to not mix the two problems I think.

> Anyone has a good reference to a serious (preferrably reviewed &
> published) paper [1] describing the incremental algorithm accurately?
>   
I'll see what I have.

Bruno