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ntn_base_friction.cc
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			/**
			* @file ntn_base_friction.cc
			*
			* @author David Simon Kammer <david.kammer@epfl.ch>
			*
			*
			* @brief implementation of ntn base friction
			*
			* @section LICENSE
			*
			* Copyright (©) 2010-2012, 2014 EPFL (Ecole Polytechnique Fédérale de Lausanne)
			* Laboratory (LSMS - Laboratoire de Simulation en Mécanique des Solides)
			*
			*/

			/* -------------------------------------------------------------------------- */
			// simtools
			#include "ntn_base_friction.hh"
			#include "dumper_text.hh"
			#include "dumper_nodal_field.hh"

			__BEGIN_AKANTU__

			/* -------------------------------------------------------------------------- */
			NTNBaseFriction::NTNBaseFriction(NTNBaseContact * contact,
			const FrictionID & id,
			const MemoryID & memory_id) :
			Memory(id,memory_id),
			Parsable(_st_friction, id),
			Dumpable(),
			contact(contact),
			is_sticking(0,1,true,id+":is_sticking",true,"is_sticking"),
			frictional_strength(0,1,0.,id+":frictional_strength",0.,"frictional_strength"),
			friction_traction(0,contact->getModel().getSpatialDimension(),
			0.,id+":friction_traction",0.,"friction_traction"),
			slip(0,1,0.,id+":slip",0.,"slip"),
			cumulative_slip(0,1,0.,id+":cumulative_slip",0.,"cumulative_slip"),
			slip_velocity(0,contact->getModel().getSpatialDimension(),
			0.,id+":slip_velocity",0.,"slip_velocity") {
			AKANTU_DEBUG_IN();

			this->contact->registerSynchronizedArray(this->is_sticking);
			this->contact->registerSynchronizedArray(this->frictional_strength);
			this->contact->registerSynchronizedArray(this->friction_traction);
			this->contact->registerSynchronizedArray(this->slip);
			this->contact->registerSynchronizedArray(this->cumulative_slip);
			this->contact->registerSynchronizedArray(this->slip_velocity);

			contact->getModel().setIncrementFlagOn();

			this->registerExternalDumper(contact->getDumper(),
			contact->getDefaultDumperName(),
			true);

			AKANTU_DEBUG_OUT();
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::updateSlip() {
			AKANTU_DEBUG_IN();

			SolidMechanicsModel & model = this->contact->getModel();
			UInt dim = model.getSpatialDimension();

			// synchronize increment
			this->contact->getSynchronizerRegistry()->synchronize(_gst_cf_incr);

			Array<Real> rel_tan_incr(0,dim);
			this->contact->computeRelativeTangentialField(model.getIncrement(),
			rel_tan_incr);
			Array<Real>::const_iterator< Vector<Real> > it = rel_tan_incr.begin(dim);

			UInt nb_nodes = this->contact->getNbContactNodes();
			for (UInt n=0; n<nb_nodes; ++n) {
			if (this->is_sticking(n)) {
			this->slip(n) = 0.;
			}
			else {
			const Vector<Real> & rti = it[n];
			this->slip(n) += rti.norm();
			this->cumulative_slip(n) += rti.norm();
			}
			}

			AKANTU_DEBUG_OUT();
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::computeFrictionTraction() {
			AKANTU_DEBUG_IN();

			this->computeStickTraction();
			this->computeFrictionalStrength();

			SolidMechanicsModel & model = this->contact->getModel();
			UInt dim = model.getSpatialDimension();

			// get contact arrays
			const SynchronizedArray<bool> & is_in_contact = this->contact->getIsInContact();

			Array<Real> & traction = const_cast< Array<Real> & >(this->friction_traction.getArray());
			Array<Real>::iterator< Vector<Real> > it_fric_trac = traction.begin(dim);

			this->is_sticking.clear(); // set to not sticking

			UInt nb_contact_nodes = this->contact->getNbContactNodes();
			for (UInt n=0; n<nb_contact_nodes; ++n) {
			// node pair is in contact
			if (is_in_contact(n)) {
			Vector<Real> fric_trac = it_fric_trac[n];
			// check if it is larger than frictional strength
			Real abs_fric = fric_trac.norm();
			if (abs_fric != 0.) {
			Real alpha = this->frictional_strength(n) / abs_fric;

			// larger -> sliding
			if (alpha < 1.) {
			fric_trac *= alpha;
			}
			else
			this->is_sticking(n) = true;
			}
			else {
			// frictional traction is already zero
			this->is_sticking(n) = true;
			}
			}
			}

			AKANTU_DEBUG_OUT();
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::computeStickTraction() {
			AKANTU_DEBUG_IN();

			SolidMechanicsModel & model = this->contact->getModel();
			UInt dim = model.getSpatialDimension();
			Real delta_t = model.getTimeStep();

			UInt nb_contact_nodes = this->contact->getNbContactNodes();

			// get contact arrays
			const SynchronizedArray<Real> & impedance = this->contact->getImpedance();
			const SynchronizedArray<bool> & is_in_contact = this->contact->getIsInContact();

			// pre-compute the acceleration
			// (not increment acceleration, because residual is still Kf)
			Array<Real> acceleration(model.getFEEngine().getMesh().getNbNodes(), dim, 0.);
			model.solveLumped(acceleration,
			model.getMass(),
			model.getResidual(),
			model.getBlockedDOFs(),
			model.getF_M2A());

			// compute relative normal fields of velocity and acceleration
			Array<Real> r_velo(0,dim);
			Array<Real> r_acce(0,dim);
			Array<Real> r_old_acce(0,dim);
			this->contact->computeRelativeTangentialField(model.getVelocity(), r_velo);
			this->contact->computeRelativeTangentialField(acceleration, r_acce);
			this->contact->computeRelativeTangentialField(model.getAcceleration(), r_old_acce);

			AKANTU_DEBUG_ASSERT(r_velo.getSize() == nb_contact_nodes,
			"computeRelativeNormalField does not give back arrays "
			<< "size == nb_contact_nodes. nb_contact_nodes = " << nb_contact_nodes
			<< " \| array size = " << r_velo.getSize());

			// compute tangential gap_dot array for all nodes
			Array<Real> gap_dot(nb_contact_nodes, dim);
			Real * gap_dot_p = gap_dot.storage();
			Real * r_velo_p = r_velo.storage();
			Real * r_acce_p = r_acce.storage();
			Real * r_old_acce_p = r_old_acce.storage();
			for (UInt i=0; i<nb_contact_nodes*dim; ++i) {
			gap_dot_p = r_velo_p + delta_t * r_acce_p - 0.5 delta_t * *r_old_acce_p;
			// increment pointers
			gap_dot_p++;
			r_velo_p++;
			r_acce_p++;
			r_old_acce_p++;
			}

			// compute friction traction to stop sliding
			Array<Real> & traction = const_cast< Array<Real> & >(this->friction_traction.getArray());
			Array<Real>::vector_iterator it_fric_trac = traction.begin(dim);
			for (UInt n=0; n<nb_contact_nodes; ++n) {
			Vector<Real> fric_trac = it_fric_trac[n];
			// node pair is NOT in contact
			if (!is_in_contact(n)) {
			fric_trac.clear(); // set to zero
			}

			// node pair is in contact
			else {
			// compute friction traction
			for (UInt d=0; d<dim; ++d)
			fric_trac(d) = impedance(n) * gap_dot(n,d) / 2.;
			}
			}

			AKANTU_DEBUG_OUT();
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::applyFrictionTraction() {
			AKANTU_DEBUG_IN();

			SolidMechanicsModel & model = this->contact->getModel();
			Array<Real> & residual = model.getResidual();
			UInt dim = model.getSpatialDimension();

			const SynchronizedArray<UInt> & slaves = this->contact->getSlaves();
			const SynchronizedArray<Real> & lumped_boundary_slaves = this->contact->getLumpedBoundarySlaves();

			UInt nb_contact_nodes = this->contact->getNbContactNodes();
			for (UInt n=0; n<nb_contact_nodes; ++n) {
			UInt slave = slaves(n);

			for (UInt d=0; d<dim; ++d) {
			residual(slave, d) -= lumped_boundary_slaves(n) * this->friction_traction(n,d);
			}
			}


			AKANTU_DEBUG_OUT();
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::registerSynchronizedArray(SynchronizedArrayBase & array) {
			AKANTU_DEBUG_IN();

			this->frictional_strength.registerDependingArray(array);

			AKANTU_DEBUG_OUT();
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::dumpRestart(const std::string & file_name) const {
			AKANTU_DEBUG_IN();

			this->is_sticking.dumpRestartFile(file_name);
			this->frictional_strength.dumpRestartFile(file_name);
			this->friction_traction.dumpRestartFile(file_name);
			this->slip.dumpRestartFile(file_name);
			this->cumulative_slip.dumpRestartFile(file_name);
			this->slip_velocity.dumpRestartFile(file_name);

			AKANTU_DEBUG_OUT();
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::readRestart(const std::string & file_name) {
			AKANTU_DEBUG_IN();

			this->is_sticking.readRestartFile(file_name);
			this->frictional_strength.readRestartFile(file_name);
			this->friction_traction.readRestartFile(file_name);
			this->cumulative_slip.readRestartFile(file_name);
			this->slip_velocity.readRestartFile(file_name);

			AKANTU_DEBUG_OUT();
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::setParam(const std::string & name, UInt node, Real value) {
			AKANTU_DEBUG_IN();

			SynchronizedArray<Real> & array = this->get< SynchronizedArray<Real> >(name);
			Int index = this->contact->getNodeIndex(node);
			if (index < 0) {
			AKANTU_DEBUG_WARNING("Node " << node << " is not a contact node. "
			<< "Therefore, cannot set interface parameter!!");
			}
			else {
			array(index) = value; // put value
			}

			AKANTU_DEBUG_OUT();
			};

			/* -------------------------------------------------------------------------- */
			UInt NTNBaseFriction::getNbStickingNodes() const {
			AKANTU_DEBUG_IN();

			UInt nb_stick = 0;

			UInt nb_nodes = this->contact->getNbContactNodes();
			const SynchronizedArray<UInt> & nodes = this->contact->getSlaves();
			const SynchronizedArray<bool> & is_in_contact = this->contact->getIsInContact();

			const Mesh & mesh = this->contact->getModel().getMesh();

			for (UInt n = 0; n < nb_nodes; ++n) {
			bool is_local_node = mesh.isLocalOrMasterNode(nodes(n));
			bool is_pbc_slave_node = this->contact->getModel().isPBCSlaveNode(nodes(n));
			if (is_local_node
			&& !is_pbc_slave_node
			&& is_in_contact(n)
			&& this->is_sticking(n)) {
			nb_stick++;
			}
			}

			StaticCommunicator::getStaticCommunicator().allReduce(&nb_stick, 1, _so_sum);

			AKANTU_DEBUG_OUT();
			return nb_stick;
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::printself(std::ostream & stream, int indent) const {
			AKANTU_DEBUG_IN();
			std::string space;
			for(Int i = 0; i < indent; i++, space += AKANTU_INDENT);

			stream << space << "NTNBaseFriction [" << std::endl;
			Parsable::printself(stream, indent);
			stream << space << "]" << std::endl;


			AKANTU_DEBUG_OUT();
			}

			/* -------------------------------------------------------------------------- */
			void NTNBaseFriction::addDumpFieldToDumper(const std::string & dumper_name,
			const std::string & field_id) {
			AKANTU_DEBUG_IN();

			#ifdef AKANTU_USE_IOHELPER
			// const SynchronizedArray<UInt> * nodal_filter = &(this->contact->getSlaves());

			if(field_id == "is_sticking") {
			this->internalAddDumpFieldToDumper(dumper_name,
			field_id,
			new dumper::NodalField<bool>(this->is_sticking.getArray()));
			}
			else if(field_id == "frictional_strength") {
			this->internalAddDumpFieldToDumper(dumper_name,
			field_id,
			new dumper::NodalField<Real>(this->frictional_strength.getArray()));
			}
			else if(field_id == "friction_traction") {
			this->internalAddDumpFieldToDumper(dumper_name,
			field_id,
			new dumper::NodalField<Real>(this->friction_traction.getArray()));
			}
			else if(field_id == "slip") {
			this->internalAddDumpFieldToDumper(dumper_name,
			field_id,
			new dumper::NodalField<Real>(this->slip.getArray()));
			}
			else if(field_id == "cumulative_slip") {
			this->internalAddDumpFieldToDumper(dumper_name,
			field_id,
			new dumper::NodalField<Real>(this->cumulative_slip.getArray()));
			}
			else if(field_id == "slip_velocity") {
			this->internalAddDumpFieldToDumper(dumper_name,
			field_id,
			new dumper::NodalField<Real>(this->slip_velocity.getArray()));
			}
			else {
			this->contact->addDumpFieldToDumper(dumper_name, field_id);
			}

			#endif

			AKANTU_DEBUG_OUT();
			}



			__END_AKANTU__

rAKA/extra_packages/traction-at-split-node-contact/src/ntn_contact/ntn_base_friction.cc5d56e862d8fcreleases/10.1007/s40571…

ntn_base_friction.ccView Options

rAKA/extra_packages/traction-at-split-node-contact/src/ntn_contact/ntn_base_friction.cc
5d56e862d8fcreleases/10.1007/s40571…

ntn_base_friction.cc
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