contact_detector_internodes.cc
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contact_detector_internodes.cc
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			/**
			* @file contact_detector_internodes.cc
			*
			* @author Moritz Waldleben <moritz.waldleben@epfl.ch>
			*
			* @date creation: Thu Jul 09 2022
			* @date last modification: Thu Jul 17 2022
			*
			* @brief Algorithm to detetect contact nodes
			*
			*
			* @section LICENSE
			*
			* Copyright (©) 2010-2021 EPFL (Ecole Polytechnique Fédérale de Lausanne)
			* Laboratory (LSMS - Laboratoire de Simulation en Mécanique des Solides)
			*
			* Akantu is free software: you can redistribute it and/or modify it under the
			* terms of the GNU Lesser General Public License as published by the Free
			* Software Foundation, either version 3 of the License, or (at your option) any
			* later version.
			*
			* Akantu is distributed in the hope that it will be useful, but WITHOUT ANY
			* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
			* A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
			* details.
			*
			* You should have received a copy of the GNU Lesser General Public License
			* along with Akantu. If not, see <http://www.gnu.org/licenses/>.
			*
			*/

			/* -------------------------------------------------------------------------- */
			#include "contact_detector_internodes.hh"
			#include "element_group.hh"
			#include "node_group.hh"
			#include "parsable.hh"
			/* -------------------------------------------------------------------------- */

			namespace akantu {

			/* -------------------------------------------------------------------------- */
			ContactDetectorInternodes::ContactDetectorInternodes(Mesh & mesh, const ID & id)
			: Parsable(ParserType::_contact_detector, id), mesh(mesh) {

			this->spatial_dimension = mesh.getSpatialDimension();

			const Parser & parser = getStaticParser();
			const ParserSection & section =
			*(parser.getSubSections(ParserType::_contact_detector).first);

			this->parseSection(section);

			auto & initial_master_node_group = mesh.createNodeGroup("initial_contact_master_nodes");
			auto & initial_slave_node_group = mesh.createNodeGroup("initial_contact_slave_nodes");

			auto & master_node_group = mesh.createNodeGroup("contact_master_nodes");
			auto & slave_node_group = mesh.createNodeGroup("contact_slave_nodes");

			initial_master_node_group.append(
			mesh.getElementGroup(id_master_nodes).getNodeGroup());
			initial_slave_node_group.append(mesh.getElementGroup(id_slave_nodes).getNodeGroup());

			master_node_group.append(
			mesh.getElementGroup(id_master_nodes).getNodeGroup());
			slave_node_group.append(mesh.getElementGroup(id_slave_nodes).getNodeGroup());
			}

			/* -------------------------------------------------------------------------- */
			void ContactDetectorInternodes::parseSection(const ParserSection & section) {
			this->id_master_nodes = section.getParameterValue<std::string>("master");
			this->id_slave_nodes = section.getParameterValue<std::string>("slave");
			}

			/* -------------------------------------------------------------------------- */
			NodeGroup & ContactDetectorInternodes::getInitialMasterNodeGroup() {
			return mesh.getNodeGroup("initial_contact_master_nodes");
			}

			/* -------------------------------------------------------------------------- */
			NodeGroup & ContactDetectorInternodes::getInitialSlaveNodeGroup() {
			return mesh.getNodeGroup("initial_contact_slave_nodes");
			}

			/* -------------------------------------------------------------------------- */
			NodeGroup & ContactDetectorInternodes::getMasterNodeGroup() {
			return mesh.getNodeGroup("contact_master_nodes");
			}

			/* -------------------------------------------------------------------------- */
			NodeGroup & ContactDetectorInternodes::getSlaveNodeGroup() {
			return mesh.getNodeGroup("contact_slave_nodes");
			}

			/* -------------------------------------------------------------------------- */
			void ContactDetectorInternodes::findContactNodes() {
			auto & master_node_group = getMasterNodeGroup();
			auto & slave_node_group = getSlaveNodeGroup();

			bool still_isolated_nodes = true;
			int iteration = 0;
			while(still_isolated_nodes) {
			auto && nb_slave_nodes_inside_radius = computeRadiuses(master_radiuses,
			master_node_group, slave_node_group);
			auto && nb_master_nodes_inside_radius = computeRadiuses(slave_radiuses,
			slave_node_group, master_node_group);

			still_isolated_nodes = false;

			for (auto && data : enumerate(master_node_group.getNodes())) {
			if (nb_master_nodes_inside_radius(std::get<0>(data)) == 0) {
			master_node_group.remove(std::get<1>(data));
			still_isolated_nodes = true;
			}
			}

			master_node_group.optimize();
			slave_node_group.optimize();
			}
			}

			/* -------------------------------------------------------------------------- */
			Matrix<Real> ContactDetectorInternodes::constructInterpolationMatrix(
			const NodeGroup & ref_node_group, const NodeGroup & eval_node_group,
			Array<Real> eval_radiuses) {
			auto && phi_eval_eval =
			constructPhiMatrix(eval_node_group, eval_node_group, eval_radiuses);
			auto && phi_ref_eval =
			constructPhiMatrix(ref_node_group, eval_node_group, eval_radiuses);

			Matrix<Real> phi_eval_eval_inv(eval_node_group.size(),
			eval_node_group.size(), 1.);

			phi_eval_eval_inv.inverse(phi_eval_eval);
			auto && interpol_ref_eval = phi_ref_eval * phi_eval_eval_inv;

			Vector<Real> ones(eval_node_group.size(), 1);
			ones.set(1.0);
			for (UInt i : arange(ref_node_group.size())) {
			Real row_sum = 0.;
			for (UInt k : arange(eval_node_group.size())) {
			row_sum = row_sum + interpol_ref_eval(i, k);
			}
			for (UInt j : arange(eval_node_group.size())) {
			interpol_ref_eval(i, j) = interpol_ref_eval(i, j) / row_sum;
			}
			}

			// extended to 2D
			Matrix<Real> interpol_ref_eval_ext(spatial_dimension*interpol_ref_eval.rows(),
			spatial_dimension*interpol_ref_eval.cols(), 0.);

			for (UInt i : arange(interpol_ref_eval.rows())) {
			for (UInt j : arange(interpol_ref_eval.cols())) {
			for (int dim = 0; dim < spatial_dimension; dim++) {
			interpol_ref_eval_ext(spatial_dimensioni+dim, spatial_dimensionj+dim) = interpol_ref_eval(i, j);
			}
			}
			}

			return interpol_ref_eval_ext;
			}

			/* -------------------------------------------------------------------------- */
			Matrix<Real>
			ContactDetectorInternodes::constructPhiMatrix(const NodeGroup & ref_node_group,
			const NodeGroup & eval_node_group, Array<Real> & eval_radiuses) {
			auto && positions = mesh.getNodes();
			auto && positions_view = make_view(positions, spatial_dimension).begin();

			Array<Real> distances(eval_node_group.size());
			Matrix<Real> phi(ref_node_group.size(), eval_node_group.size());
			phi.set(0.);

			for (auto && ref_node_data : enumerate(ref_node_group.getNodes())) {
			auto i = std::get<0>(ref_node_data);
			auto ref_node = std::get<1>(ref_node_data);

			computeDistancesToRefNode(ref_node, eval_node_group, distances);

			for (UInt j : arange(eval_node_group.size())) {
			if (distances(j) <= eval_radiuses(j)) {
			phi(i, j) = computeRadialBasisInterpolation(distances(j),
			eval_radiuses(j));
			}
			}
			}

			return phi;
			}

			/* -------------------------------------------------------------------------- */
			Array<UInt>
			ContactDetectorInternodes::computeRadiuses(Array<Real> & attack_radiuses,
			const NodeGroup & ref_node_group, const NodeGroup & eval_node_group,
			Real c, Real C, Real d, const UInt max_iter) {
			// maximum number of support nodes
			UInt f = std::floor(1 / (std::pow(1 - c, 4) * (1 + 4 * c)));

			Array<Real> distances_neighboors(ref_node_group.size());
			Array<Real> distances_opposites(eval_node_group.size());

			attack_radiuses.resize(ref_node_group.size());

			Array<UInt> nb_neighboor_nodes_inside_radiuses(ref_node_group.size(), 1, 0);
			Array<UInt> nb_opposite_nodes_inside_radiuses(eval_node_group.size(), 1, 0);

			UInt nb_iter = 0;
			UInt max_nb_supports = std::numeric_limits<int>::max();

			while (max_nb_supports > f && nb_iter < max_iter) {
			for (auto && ref_node_data : enumerate(ref_node_group.getNodes())) {
			auto j = std::get<0>(ref_node_data);
			auto ref_node = std::get<1>(ref_node_data);

			// distances to all nodes on same surface (aka neighboors)
			computeDistancesToRefNode(ref_node, ref_node_group, distances_neighboors);

			// get distances to all nodes on other surface (aka opposites)
			computeDistancesToRefNode(ref_node, eval_node_group, distances_opposites);

			// minimal distance to neighboors i.e radius of "attack"
			// TODO: could be done in computeDistancesToRefNode method
			Real attack_radius = std::numeric_limits<double>::max();

			// compute radius of attack
			for (auto && neighboor_node_data : enumerate(ref_node_group.getNodes())) {
			auto i = std::get<0>(neighboor_node_data);
			auto neighboor_node = std::get<1>(neighboor_node_data);

			if (neighboor_node != ref_node) {
			if (distances_neighboors(i) <= attack_radius) {
			attack_radius = distances_neighboors(i);
			}
			}
			}

			Real correction_radius =
			std::sqrt(d * d + 0.25 * std::pow(attack_radius, 2));
			correction_radius = std::max<Real>(attack_radius, correction_radius);

			if (correction_radius > attack_radius / c) {
			attack_radius = correction_radius / c;
			} else {
			attack_radius = correction_radius;
			}
			attack_radiuses(j) = attack_radius;

			// compute number of neighboor nodes inside radius
			for (UInt i : arange(ref_node_group.size())) {
			if (distances_neighboors(i) < attack_radius) {
			nb_neighboor_nodes_inside_radiuses(i)++;
			}
			}

			// compute number of opposite nodes inside C*radius
			for (UInt i : arange(eval_node_group.size())) {
			if (distances_opposites(i) < C * attack_radius) {
			nb_opposite_nodes_inside_radiuses(i)++;
			}
			}
			}

			// maximum number of neighboors inside radius
			// aka maximum number of supports
			max_nb_supports = 0;
			for (auto nb_neighboors : nb_neighboor_nodes_inside_radiuses) {
			if (nb_neighboors > max_nb_supports) {
			max_nb_supports = nb_neighboors;
			}
			}

			// correct maximum number of support nodes
			if (max_nb_supports > f) {
			c = 0.5 * (1 + c);
			f = floor(1 / (pow(1 - c, 4) * (1 + 4 * c)));

			nb_neighboor_nodes_inside_radiuses.set(0);
			nb_opposite_nodes_inside_radiuses.set(0);

			nb_iter++;
			}
			}

			if (nb_iter == max_iter) {
			AKANTU_EXCEPTION(nb_iter << " exceeds the maximum number of iterations");
			}

			return nb_opposite_nodes_inside_radiuses;
			}

			/* -------------------------------------------------------------------------- */
			void ContactDetectorInternodes::computeDistancesToRefNode(
			UInt & ref_node, const NodeGroup & eval_node_group,
			Array<Real> & out_array) {
			auto && positions = mesh.getNodes();
			auto && positions_view = make_view(positions, spatial_dimension).begin();
			Vector<Real> ref_pos = positions_view[ref_node];

			for (auto && eval_node_data : enumerate(eval_node_group.getNodes())) {
			auto i = std::get<0>(eval_node_data);
			auto eval_node = std::get<1>(eval_node_data);

			auto && pos_eval = positions_view[eval_node];
			out_array(i) = ref_pos.distance(pos_eval);
			}
			}

			/* -------------------------------------------------------------------------- */
			Real ContactDetectorInternodes::computeRadialBasisInterpolation(
			const Real distance, const Real radius) {
			/// rescaled radial basis function: Wendland
			Real ratio = distance / radius;
			Real phi_of_x = std::pow(1 - ratio, 4) * (1 + 4 * ratio);
			return phi_of_x;
			}

			} // namespace akantu

rAKA/src/model/contact_mechanics_internodes/contact_detector_internodes.ccca0328ce3b3bmaster

contact_detector_internodes.ccView Options

rAKA/src/model/contact_mechanics_internodes/contact_detector_internodes.cc
ca0328ce3b3bmaster

contact_detector_internodes.cc
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