yade-dev team mailing list archive

[Anton Gladky <gladky.anton@xxxxxxxxx>]

Ok, thank you all.
Will try to test and calibrate it.
______________________________

Anton Gladkyy


2010/2/11 Václav Šmilauer <eudoxos@xxxxxxxx>

> What do you mean, cohesive shear force? You just change definition of
> plasticity surface to get shear resistanace when the contact is in
> tension. This is what you have currently:
>
> Real
> maxFsSq=phys->normalForce.SquaredLength()*phys->tanFrictionAngle*phys->tanFrictionAngle;
>
> so you change that accordingly. In attachment, there are some plasticity
> surfaces used in the concrete model. Those for ω=1 (damaged) carry no
> cohesion (that is what you have now), undamaged (ω=0) ones do have
> cohesion, which is what you need. (Horizontal axis is normal stress,
> vertical is |shear stress|). (Disregard those log surfaces, they are not
> relevant here)
>
> So if you go with this kind of linear plasticity surface, you need one
> additional parameter (e.g. cohesion=max normal stress=x-coordinate of
> the cone top):
>
> Real maxFs=max((Real)0.,cohesion-sigmaN*tanFrictionAngle);
> if(sigmaT.SquaredLength()>maxFs*maxFs){
>        // plastic slip
> }
>
> See e.g. http://en.wikipedia.org/wiki/Yield_%28engineering%29, but they
> have plasticity surfaces defined in terms of 3 principal stresses,
> whereas we have to use formulation with σn vs. |σt| with DEM (at least
> for 3 degrees of freedom of the contact), which corresponds to taking
> σ₁=σn and σ₂=σ₃=|σt| (I think; never thought about that properly).
>
> Cheers, Vaclav
>
>
>
>
> > Hi,
> >
> > I am trying to add "shear cohesive force" into the RockPM, as for now
> > there are only normal cohesive forces. Has anybody an advice where to
> > get such algorithm to escape write it from scratch?
> >
> > Thanks for all suggestions.
> > ______________________________
> >
> > Anton Gladkyy
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