void PolyhedraSplitter::action()
{
const shared_ptr<Scene> _rb=shared_ptr<Scene>();
shared_ptr<Scene> rb=(_rb?_rb:Omega::instance().getScene());
vector<PSplitT> splitsV;
vector<Matrix3r> bStresses (scene->bodies->size(), Matrix3r::Zero());
getStressForEachBody(bStresses);
FOREACH(const shared_ptr<Body>& b, *rb->bodies){
if(!b || !b->material || !b->shape) continue;
shared_ptr<Polyhedra> p=YADE_PTR_DYN_CAST<Polyhedra>(b->shape);
shared_ptr<PolyhedraMat> m=YADE_PTR_DYN_CAST<PolyhedraMat>(b->material);
if(p && m->IsSplitable){
//not real strees, to get real one, it has to be divided by body volume
Matrix3r stress = bStresses[b->id];
//get eigenstresses
Symmetrize(stress);
Matrix3r I_vect(Matrix3r::Zero()), I_valu(Matrix3r::Zero());
matrixEigenDecomposition(stress,I_vect,I_valu);
Eigen::Matrix3f::Index min_i, max_i;
I_valu.diagonal().minCoeff(&min_i);
I_valu.diagonal().maxCoeff(&max_i);
//division of stress by volume
const Vector3r dirC = I_vect.col(max_i);
const Vector3r dirT = I_vect.col(min_i);
const Vector3r dir1 = dirC.normalized() + dirT.normalized();
const Vector3r dir2 = dirC.normalized() - dirT.normalized();
//double sigma_t = -comp_stress/2.+ tens_stress;
const Real sigma_t = pow((
pow(I_valu(0,0)-I_valu(1,1),2)+
pow(I_valu(0,0)-I_valu(2,2),2)+
pow(I_valu(1,1)-I_valu(2,2),2))
/2.,0.5)/p->GetVolume();
if (sigma_t > getStrength(p->GetVolume(),m->GetStrength())) {
splitsV.push_back(std::make_tuple(b, dir1.normalized(), dir2.normalized()));
}
}
}
std::for_each(splitsV.begin(), splitsV.end(), &SplitPolyhedraDouble);
}
/* Law2_ScGeom_ViscElPhys_Basic */
void Law2_ScGeom_ViscElPhys_Basic::go(shared_ptr<IGeom>& _geom, shared_ptr<IPhys>& _phys, Interaction* I){
const ScGeom& geom=*static_cast<ScGeom*>(_geom.get());
ViscElPhys& phys=*static_cast<ViscElPhys*>(_phys.get());
const int id1 = I->getId1();
const int id2 = I->getId2();
if (geom.penetrationDepth<0) {
if (phys.liqBridgeCreated and -geom.penetrationDepth<phys.sCrit and phys.Capillar) {
phys.normalForce = -calculateCapillarForce(geom, phys)*geom.normal;
if (I->isActive) {
addForce (id1,-phys.normalForce,scene);
addForce (id2, phys.normalForce,scene);
};
return;
} else {
scene->interactions->requestErase(I);
return;
};
};
const BodyContainer& bodies = *scene->bodies;
const State& de1 = *static_cast<State*>(bodies[id1]->state.get());
const State& de2 = *static_cast<State*>(bodies[id2]->state.get());
/*
* This part for implementation of the capillar model.
* All main equations are in calculateCapillarForce function.
* There is only the determination of critical distance between spheres,
* after that the liquid bridge will be broken.
*/
if (not(phys.liqBridgeCreated) and phys.Capillar) {
phys.liqBridgeCreated = true;
Sphere* s1=dynamic_cast<Sphere*>(bodies[id1]->shape.get());
Sphere* s2=dynamic_cast<Sphere*>(bodies[id2]->shape.get());
if (s1 and s2) {
phys.R = 2 * s1->radius * s2->radius / (s1->radius + s2->radius);
} else if (s1 and not(s2)) {
phys.R = s1->radius;
} else {
phys.R = s2->radius;
}
const Real Vstar = phys.Vb/(phys.R*phys.R*phys.R);
const Real Sstar = (1+0.5*phys.theta)*(pow(Vstar,1/3.0) + 0.1*pow(Vstar,2.0/3.0)); // [Willett2000], equation (15), use the full-length e.g 2*Sc
phys.sCrit = Sstar*phys.R;
}
Vector3r& shearForce = phys.shearForce;
if (I->isFresh(scene)) shearForce=Vector3r(0,0,0);
const Real& dt = scene->dt;
shearForce = geom.rotate(shearForce);
// Handle periodicity.
const Vector3r shift2 = scene->isPeriodic ? scene->cell->intrShiftPos(I->cellDist): Vector3r::Zero();
const Vector3r shiftVel = scene->isPeriodic ? scene->cell->intrShiftVel(I->cellDist): Vector3r::Zero();
const Vector3r c1x = (geom.contactPoint - de1.pos);
const Vector3r c2x = (geom.contactPoint - de2.pos - shift2);
const Vector3r relativeVelocity = (de1.vel+de1.angVel.cross(c1x)) - (de2.vel+de2.angVel.cross(c2x)) + shiftVel;
const Real normalVelocity = geom.normal.dot(relativeVelocity);
const Vector3r shearVelocity = relativeVelocity-normalVelocity*geom.normal;
// As Chiara Modenese suggest, we store the elastic part
// and then add the viscous part if we pass the Mohr-Coulomb criterion.
// See http://www.mail-archive.com/[email protected]/msg01391.html
shearForce += phys.ks*dt*shearVelocity; // the elastic shear force have a history, but
Vector3r shearForceVisc = Vector3r::Zero(); // the viscous shear damping haven't a history because it is a function of the instant velocity
// Prevent appearing of attraction forces due to a viscous component
// [Radjai2011], page 3, equation [1.7]
// [Schwager2007]
const Real normForceReal = phys.kn * geom.penetrationDepth + phys.cn * normalVelocity;
if (normForceReal < 0) {
phys.normalForce = Vector3r::Zero();
} else {
phys.normalForce = normForceReal * geom.normal;
}
Vector3r momentResistance = Vector3r::Zero();
if (phys.mR>0.0) {
const Vector3r relAngVel = de1.angVel - de2.angVel;
relAngVel.normalized();
if (phys.mRtype == 1) {
momentResistance = -phys.mR*phys.normalForce.norm()*relAngVel; // [Zhou1999536], equation (3)
} else if (phys.mRtype == 2) {
momentResistance = -phys.mR*(c1x.cross(de1.angVel) - c2x.cross(de2.angVel)).norm()*phys.normalForce.norm()*relAngVel; // [Zhou1999536], equation (4)
}
}
const Real maxFs = phys.normalForce.squaredNorm() * std::pow(phys.tangensOfFrictionAngle,2);
if( shearForce.squaredNorm() > maxFs )
{
// Then Mohr-Coulomb is violated (so, we slip),
// we have the max value of the shear force, so
// we consider only friction damping.
const Real ratio = sqrt(maxFs) / shearForce.norm();
shearForce *= ratio;
}
else
{
// Then no slip occurs we consider friction damping + viscous damping.
shearForceVisc = phys.cs*shearVelocity;
}
if (I->isActive) {
const Vector3r f = phys.normalForce + shearForce + shearForceVisc;
addForce (id1,-f,scene);
addForce (id2, f,scene);
addTorque(id1,-c1x.cross(f)+momentResistance,scene);
addTorque(id2, c2x.cross(f)-momentResistance,scene);
}
}
bool computeForceTorqueViscEl(shared_ptr<IGeom>& _geom, shared_ptr<IPhys>& _phys, Interaction* I, Vector3r & force, Vector3r & torque1, Vector3r & torque2) {
ViscElPhys& phys=*static_cast<ViscElPhys*>(_phys.get());
const ScGeom& geom=*static_cast<ScGeom*>(_geom.get());
Scene* scene=Omega::instance().getScene().get();
#ifdef YADE_SPH
//=======================================================================================================
if (phys.SPHmode) {
if (computeForceSPH(_geom, _phys, I, force)) {
return true;
} else {
return false;
}
}
//=======================================================================================================
#endif
const int id1 = I->getId1();
const int id2 = I->getId2();
if (geom.penetrationDepth<0) {
return false;
} else {
const BodyContainer& bodies = *scene->bodies;
const State& de1 = *static_cast<State*>(bodies[id1]->state.get());
const State& de2 = *static_cast<State*>(bodies[id2]->state.get());
Vector3r& shearForce = phys.shearForce;
if (I->isFresh(scene)) shearForce=Vector3r(0,0,0);
const Real& dt = scene->dt;
shearForce = geom.rotate(shearForce);
// Handle periodicity.
const Vector3r shift2 = scene->isPeriodic ? scene->cell->intrShiftPos(I->cellDist): Vector3r::Zero();
const Vector3r shiftVel = scene->isPeriodic ? scene->cell->intrShiftVel(I->cellDist): Vector3r::Zero();
const Vector3r c1x = (geom.contactPoint - de1.pos);
const Vector3r c2x = (geom.contactPoint - de2.pos - shift2);
const Vector3r relativeVelocity = (de1.vel+de1.angVel.cross(c1x)) - (de2.vel+de2.angVel.cross(c2x)) + shiftVel;
const Real normalVelocity = geom.normal.dot(relativeVelocity);
const Vector3r shearVelocity = relativeVelocity-normalVelocity*geom.normal;
// As Chiara Modenese suggest, we store the elastic part
// and then add the viscous part if we pass the Mohr-Coulomb criterion.
// See http://www.mail-archive.com/[email protected]/msg01391.html
shearForce += phys.ks*dt*shearVelocity; // the elastic shear force have a history, but
Vector3r shearForceVisc = Vector3r::Zero(); // the viscous shear damping haven't a history because it is a function of the instant velocity
// Prevent appearing of attraction forces due to a viscous component
// [Radjai2011], page 3, equation [1.7]
// [Schwager2007]
phys.Fn = phys.kn * geom.penetrationDepth;
phys.Fv = phys.cn * normalVelocity;
const Real normForceReal = phys.Fn + phys.Fv;
if (normForceReal < 0) {
phys.normalForce = Vector3r::Zero();
} else {
phys.normalForce = normForceReal * geom.normal;
}
Vector3r momentResistance = Vector3r::Zero();
if (phys.mR>0.0) {
const Vector3r relAngVel = de1.angVel - de2.angVel;
relAngVel.normalized();
if (phys.mRtype == 1) {
momentResistance = -phys.mR*phys.normalForce.norm()*relAngVel; // [Zhou1999536], equation (3)
} else if (phys.mRtype == 2) {
momentResistance = -phys.mR*(c1x.cross(de1.angVel) - c2x.cross(de2.angVel)).norm()*phys.normalForce.norm()*relAngVel; // [Zhou1999536], equation (4)
}
}
const Real maxFs = phys.normalForce.squaredNorm() * std::pow(phys.tangensOfFrictionAngle,2);
if( shearForce.squaredNorm() > maxFs )
{
// Then Mohr-Coulomb is violated (so, we slip),
// we have the max value of the shear force, so
// we consider only friction damping.
const Real ratio = sqrt(maxFs) / shearForce.norm();
shearForce *= ratio;
}
else
{
// Then no slip occurs we consider friction damping + viscous damping.
shearForceVisc = phys.cs*shearVelocity;
}
force = phys.normalForce + shearForce + shearForceVisc;
torque1 = -c1x.cross(force)+momentResistance;
torque2 = c2x.cross(force)-momentResistance;
return true;
}
}
