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ntrf_contact.cc
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Wed, Dec 11, 10:29

ntrf_contact.cc
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/**
* @file ntrf_contact.cc
* @author David Kammer <david.kammer@epfl.ch>
* @date Thu Mar 14 14:16:07 2013
*
* @brief
*
* @section LICENSE
*
* Copyright (©) 2010-2011 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 "ntrf_contact.hh"
__BEGIN_SIMTOOLS__
/* -------------------------------------------------------------------------- */
NTRFContact::NTRFContact(SolidMechanicsModel & model,
const ContactID & id,
const MemoryID & memory_id) :
Memory(memory_id), id(id), model(model),
slaves(0,1,0,id+":slaves",std::numeric_limits<UInt>::quiet_NaN(),"slaves"),
contact_pressure(0,model.getSpatialDimension(),0,id+":contact_pressure",
std::numeric_limits<Real>::quiet_NaN(),"contact_pressure"),
is_in_contact(0,1,false,id+":is_in_contact",false,"is_in_contact"),
lumped_boundary(0,1,0,id+":lumped_boundary",
std::numeric_limits<Real>::quiet_NaN(),"lumped_boundary"),
reference_point(0,model.getSpatialDimension()),
normal(0,model.getSpatialDimension()),
contact_surfaces()
{
AKANTU_DEBUG_IN();
FEM & boundary_fem = this->model.getFEMBoundary();
boundary_fem.initShapeFunctions();
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::setReferencePoint(Real x, Real y, Real z) {
AKANTU_DEBUG_IN();
Real coord[3];
coord[0] = x;
coord[1] = y;
coord[2] = z;
this->reference_point.resize(1);
UInt dim = this->model.getSpatialDimension();
for (UInt d=0; d<dim; ++d)
this->reference_point(0,d) = coord[d];
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::setNormal(Real x, Real y, Real z) {
AKANTU_DEBUG_IN();
UInt dim = this->model.getSpatialDimension();
Real coord[3];
coord[0] = x;
coord[1] = y;
coord[2] = z;
if (dim == 2)
Math::normalize2(coord);
else if (dim == 3)
Math::normalize3(coord);
else
AKANTU_DEBUG_ERROR("setNormal in NTRFContact not implemented for dimension " << dim);
this->normal.resize(1);
for (UInt d=0; d<dim; ++d)
this->normal(0,d) = coord[d];
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::addSurface(Surface surf) {
AKANTU_DEBUG_IN();
UInt dim = this->model.getSpatialDimension();
this->contact_surfaces.insert(surf);
// get all nodes for all surfaces
CSR<UInt> all_surface_nodes;
MeshUtils::buildNodesPerSurface(this->model.getFEM().getMesh(), all_surface_nodes);
// find slave nodes
for(CSR<UInt>::iterator snode = all_surface_nodes.begin(surf);
snode != all_surface_nodes.end(surf);
++snode) {
this->addNode(*snode);
}
// synchronize with depending nodes
updateInternalData();
syncArrays(_added);
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::addNode(UInt node) {
AKANTU_DEBUG_IN();
UInt dim = this->model.getSpatialDimension();
// add to node arrays
this->slaves.push_back(node);
// set contact as false
this->is_in_contact.push_back(false);
// before initializing
// set contact pressure, normal, lumped_boundary to Nan
this->contact_pressure.push_back(std::numeric_limits<Real>::quiet_NaN());
this->lumped_boundary.push_back(std::numeric_limits<Real>::quiet_NaN());
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::addNodes(Array<UInt> & nodes) {
AKANTU_DEBUG_IN();
UInt nb_nodes = nodes.getSize();
UInt nb_compo = nodes.getNbComponent();
for (UInt n=0; n<nb_nodes; ++n) {
for (UInt c=0; c<nb_compo; ++c) {
this->addNode(nodes(n,c));
}
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::registerSyncronizedArray(SyncronizedArrayBase & array) {
AKANTU_DEBUG_IN();
this->slaves.registerDependingArray(array);
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::dumpRestart(const std::string & file_name) const {
AKANTU_DEBUG_IN();
this->slaves.dumpRestartFile(file_name);
this->is_in_contact.dumpRestartFile(file_name);
this->contact_pressure.dumpRestartFile(file_name);
this->lumped_boundary.dumpRestartFile(file_name);
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::readRestart(const std::string & file_name) {
AKANTU_DEBUG_IN();
this->slaves.readRestartFile(file_name);
this->is_in_contact.readRestartFile(file_name);
this->contact_pressure.readRestartFile(file_name);
this->lumped_boundary.readRestartFile(file_name);
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::updateInternalData() {
AKANTU_DEBUG_IN();
updateLumpedBoundary();
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::updateLumpedBoundary() {
AKANTU_DEBUG_IN();
// set all values in lumped_boundary to zero
this->lumped_boundary.clear();
UInt dim = this->model.getSpatialDimension();
UInt nb_contact_nodes = getNbContactNodes();
const FEM & boundary_fem = this->model.getFEMBoundary();
const Mesh & mesh = this->model.getFEM().getMesh();
Mesh::type_iterator it = mesh.firstType(dim-1);
Mesh::type_iterator last = mesh.lastType(dim-1);
for (; it != last; ++it) {
// get elements connected to each node
CSR<UInt> node_to_element;
MeshUtils::buildNode2ElementsByElementType(mesh, *it, node_to_element);
UInt nb_nodes_per_element = mesh.getNbNodesPerElement(*it);
const Array<UInt> & connectivity = mesh.getConnectivity(*it);
// get shapes and compute integral
const Array<Real> & shapes = boundary_fem.getShapes(*it);
Array<Real> area(mesh.getNbElement(*it),nb_nodes_per_element);
boundary_fem.integrate(shapes,area,nb_nodes_per_element,*it);
// get surface id information
const Array<UInt> & surface_id = mesh.getSurfaceID(*it);
std::set<UInt>::iterator pos;
std::set<UInt>::iterator end = this->contact_surfaces.end();
if (this->contact_surfaces.size() == 0)
std::cerr << "No surfaces in ntrf contact. You have to define the lumped boundary by yourself." << std::endl;
// loop over contact nodes
for (UInt i=0; i<nb_contact_nodes; ++i) {
UInt node = this->slaves(i);
CSR<UInt>::iterator elem = node_to_element.begin(node);
// loop over all elements connected to this node
for (; elem != node_to_element.end(node); ++elem) {
UInt e = *elem;
// if element is not at interface continue
pos = this->contact_surfaces.find(surface_id(e));
if (pos == end)
continue;
// loop over all points of this element
for (UInt q=0; q<nb_nodes_per_element; ++q) {
if (connectivity(e,q) == node) {
this->lumped_boundary(i) += area(e,q);
}
}
}
}
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::computeContactPressure() {
AKANTU_DEBUG_IN();
UInt dim = this->model.getSpatialDimension();
Real delta_t = this->model.getTimeStep();
UInt nb_contact_nodes = getNbContactNodes();
// pre-compute the acceleration
// (not increment acceleration, because residual is still Kf)
Array<Real> acceleration(this->model.getFEM().getMesh().getNbNodes(),dim);
this->model.solveLumped(acceleration,
this->model.getMass(),
this->model.getResidual(),
this->model.getBoundary(),
this->model.getF_M2A());
const Array<Real> & residual = this->model.getResidual();
const Array<Real> & mass = this->model.getMass();
// compute relative normal fields of displacement, velocity and acceleration
Array<Real> r_disp(0,1);
Array<Real> r_velo(0,1);
Array<Real> r_acce(0,1);
Array<Real> r_old_acce(0,1);
computeNormalGap(r_disp);
computeRelativeNormalField(this->model.getVelocity(), r_velo);
computeRelativeNormalField(acceleration, r_acce);
computeRelativeNormalField(this->model.getAcceleration(), r_old_acce);
AKANTU_DEBUG_ASSERT(r_disp.getSize() == nb_contact_nodes,
"computeNormalGap does not give back arrays "
<< "size == nb_contact_nodes. nb_contact_nodes = "
<< nb_contact_nodes << " | array size = "
<< r_disp.getSize());
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 gap array for all nodes
Array<Real> gap(nb_contact_nodes, 1);
Real * gap_p = gap.storage();
Real * r_disp_p = r_disp.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; ++i) {
*gap_p = *r_disp_p + delta_t * *r_velo_p + delta_t * delta_t * *r_acce_p - 0.5 * delta_t * delta_t * *r_old_acce_p;
// increment pointers
gap_p++;
r_disp_p++;
r_velo_p++;
r_acce_p++;
r_old_acce_p++;
}
// check if gap is negative -> is in contact
for (UInt n=0; n<nb_contact_nodes; ++n) {
if (gap(n) < 0.) {
UInt node = this->slaves(n);
for (UInt d=0; d<dim; ++d) {
this->contact_pressure(n,d) = mass(node) / delta_t / delta_t
/ this->lumped_boundary(n) * gap(n) * this->normal(0,d);
/*
// from the ntn_contact:
this->contact_pressure(n,d) = this->impedance(n) * gap(n) / (2 * delta_t)
* this->normal(0,d);
*/
}
this->is_in_contact(n) = true;
}
else {
for (UInt d=0; d<dim; ++d)
this->contact_pressure(n,d) = 0.;
this->is_in_contact(n) = false;
}
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::applyContactPressure() {
AKANTU_DEBUG_IN();
UInt nb_contact_nodes = getNbContactNodes();
UInt dim = this->model.getSpatialDimension();
Array<Real> & residual = this->model.getResidual();
for (UInt n=0; n<nb_contact_nodes; ++n) {
UInt node = this->slaves(n);
for (UInt d=0; d<dim; ++d) {
residual(node, d) -= this->lumped_boundary(n) * this->contact_pressure(n,d);
}
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::computeRelativeTangentialField(const Array<Real> & field,
Array<Real> & rel_tang_field) const {
AKANTU_DEBUG_IN();
// resize arrays to zero
rel_tang_field.resize(0);
UInt dim = this->model.getSpatialDimension();
Real * field_p = field.storage();
Real * normals_p = this->normal.storage();
UInt nb_contact_nodes = this->slaves.getSize();
for (UInt n=0; n<nb_contact_nodes; ++n) {
// nodes
UInt node = this->slaves(n);
// compute relative field to master
Real rel_array[dim];
for (UInt d=0; d<dim; ++d) {
rel_array[d] = field_p[node*dim + d];
}
// compute dot product with normal of master
Real dot_prod = Math::vectorDot(normals_p, rel_array, dim);
// compute the tangential projection of the relative field to the master
for (UInt d=0; d<dim; ++d)
rel_array[d] -= dot_prod * normals_p[d];
rel_tang_field.push_back(rel_array);
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::computeNormalGap(Array<Real> & gap) const {
AKANTU_DEBUG_IN();
gap.resize(0);
UInt dim = this->model.getSpatialDimension();
Real * cur_pos = this->model.getCurrentPosition().storage();
Real * normals_p = this->normal.storage();
UInt nb_contact_nodes = this->getNbContactNodes();
for (UInt n=0; n<nb_contact_nodes; ++n) {
// nodes
UInt node = this->slaves(n);
// compute relative field to master
Real rel_array[dim];
for (UInt d=0; d<dim; ++d) {
rel_array[d] = cur_pos[node*dim + d] - this->reference_point(0,d);
}
// compute dot product with normal of master
Real dot_prod = Math::vectorDot(normals_p, rel_array, dim);
gap.push_back(dot_prod);
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::computeRelativeNormalField(const Array<Real> & field,
Array<Real> & rel_normal_field) const {
AKANTU_DEBUG_IN();
// resize arrays to zero
rel_normal_field.resize(0);
UInt dim = this->model.getSpatialDimension();
Real * field_p = field.storage();
Real * normals_p = this->normal.storage();
UInt nb_contact_nodes = this->getNbContactNodes();
for (UInt n=0; n<nb_contact_nodes; ++n) {
// nodes
UInt node = this->slaves(n);
// compute dot product with normal of master
Real dot_prod = Math::vectorDot(normals_p, &(field_p[node*dim]), dim);
rel_normal_field.push_back(dot_prod);
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
Int NTRFContact::getNodeIndex(UInt node) const {
AKANTU_DEBUG_IN();
AKANTU_DEBUG_OUT();
return this->slaves.find(node);
}
/* -------------------------------------------------------------------------- */
void NTRFContact::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 << "NTRFContact [" << std::endl;
stream << space << " + id : " << id << std::endl;
stream << space << " + slaves : " << std::endl;
this->slaves.printself(stream, indent + 2);
stream << space << " + contact_pressure : " << std::endl;
this->contact_pressure.printself(stream, indent + 2);
stream << space << "]" << std::endl;
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
void NTRFContact::syncArrays(SyncChoice sync_choice) {
AKANTU_DEBUG_IN();
this->slaves.syncElements(sync_choice);
this->is_in_contact.syncElements(sync_choice);
this->contact_pressure.syncElements(sync_choice);
this->lumped_boundary.syncElements(sync_choice);
AKANTU_DEBUG_OUT();
}
__END_SIMTOOLS__

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