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[behzad <question293758@xxxxxxxxxxxxxxxxxxxxx>]

New question #293758 on Yade:
https://answers.launchpad.net/yade/+question/293758


Hi there,

I have a cohesive contact which can break if shearAdhesion or normalAdhesion values are met by the contact force. 

These lines handle the normalAdesion part: 

  if (geom.penetrationDepth <0 && phys.fragile && phys.normalAdhesion > 0 && phys.normalForce.norm() > phys.normalAdhesion) {
	    phys.cohesionBroken= true;	
		return false;	
        }


However, the problem is in shearAdhesion part. What's the correct way to state the breakage of a cohesive contact by shear force and include the friction effect as well?
 i.e. if the shearForce.norm() > shearAdhesion, break the cohesion and now as the friction angle is bigger, the movement is more difficult. 



I got this from the other contact models in Yade. But, effect of frictionAngle is not correct this way. Because, bigger friction angle doesn't make the particles reluctant to move. 


   if (phys.fragile && phys.shearAdhesion > 0.0 && phys.shearForce.norm() > phys.shearAdhesion) {
	   	phys.SetBreakingState();	

		const Real maxFs = phys.normalForce.squaredNorm() * std::pow(phys.tanFrictionAngle,2);
		Real ratio = maxFs/ phys.shearForce.norm();
		phys.shearForce *= ratio;	
        }


Can someone help me out?
Thanks

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