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sliding_cube_2d.cc
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sliding_cube_2d.cc
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/**
* @file test_contact_rigid_sliding_cube_2d.cc
* @author David Kammer <david.kammer@epfl.ch>
* @date Tue Feb 08 15:56:42 2011
*
* @brief test rigid contact for a 2d sliding cube in explicit
*
* @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 "aka_common.hh"
#include "mesh.hh"
#include "mesh_io.hh"
#include "mesh_io_msh.hh"
#include "mesh_utils.hh"
#include "solid_mechanics_model.hh"
#include "material.hh"
#include "contact.hh"
#include "contact_rigid.hh"
#include "friction_coefficient.hh"
#include "unique_constant_fric_coef.hh"
#include "contact_neighbor_structure.hh"
#include "regular_grid_neighbor_structure.hh"
#include "contact_search.hh"
#include "contact_search_explicit.hh"
#ifdef AKANTU_USE_IOHELPER
# include "io_helper.h"
#endif //AKANTU_USE_IOHELPER
using namespace akantu;
int main(int argc, char *argv[])
{
akantu::initialize(&argc, &argv);
debug::setDebugLevel(dblWarning);
UInt dim = 2;
const ElementType element_type = _quadrangle_4; //_triangle_3;
#ifdef AKANTU_USE_IOHELPER
const UInt paraview_type = QUAD1; //TRIANGLE1;
#endif //AKANTU_USE_IOHELPER
//UInt max_steps = 200000;
UInt imposing_steps = 20000;
Real max_displacement = -0.01;
UInt damping_steps = 10000;
UInt damping_interval = 100;
Real damping_ratio = 0.5;
Real imposed_velocity = 401.92;
Real needed_time = 0.005;
UInt additional_steps = 2000;
/// load mesh
Mesh my_mesh(dim);
MeshIOMSH mesh_io;
mesh_io.read("sliding_cube_2d.msh", my_mesh);
/// build facet connectivity and surface id
MeshUtils::buildFacets(my_mesh,1,0);
MeshUtils::buildSurfaceID(my_mesh);
UInt nb_nodes = my_mesh.getNbNodes();
/// declaration of model
SolidMechanicsModel my_model(my_mesh);
/// model initialization
my_model.initExplicit();
my_model.initVectors();
// initialize the vectors
memset(my_model.getForce().values, 0, dim*nb_nodes*sizeof(Real));
memset(my_model.getVelocity().values, 0, dim*nb_nodes*sizeof(Real));
memset(my_model.getAcceleration().values, 0, dim*nb_nodes*sizeof(Real));
memset(my_model.getDisplacement().values, 0, dim*nb_nodes*sizeof(Real));
memset(my_model.getBoundary().values, false, dim*nb_nodes*sizeof(bool));
my_model.initExplicit();
my_model.initModel();
//my_model.readMaterials("material.dat");
my_model.readMaterials("material_elastic_caughey.dat");
my_model.initMaterials();
UInt nb_element = my_model.getFEM().getMesh().getNbElement(element_type);
Real time_step = my_model.getStableTimeStep();
my_model.setTimeStep(time_step/10.);
UInt max_steps = static_cast<UInt>(needed_time*10/time_step) + imposing_steps + damping_steps + additional_steps;
std::cout << "The number of time steps is found to be: " << max_steps << std::endl;
Real * velocity_val = my_model.getVelocity().values;
Real * acceleration_val = my_model.getAcceleration().values;
my_model.assembleMassLumped();
Surface impactor = 0;
Surface rigid_body_surface = 1;
Surface master = 2;
// modify surface id
UInt nb_surfaces = my_mesh.getNbSurfaces();
my_mesh.setNbSurfaces(++nb_surfaces);
ElementType surface_element_type = my_mesh.getFacetElementType(element_type);
UInt nb_surface_element = my_model.getFEM().getMesh().getNbElement(surface_element_type);
UInt * surface_id_val = my_mesh.getSurfaceID(surface_element_type).values;
for(UInt i=0; i < nb_surface_element; ++i) {
if (surface_id_val[i] == rigid_body_surface) {
Real barycenter[dim];
Real * barycenter_p = &barycenter[0];
my_mesh.getBarycenter(i,surface_element_type,barycenter_p);
if(barycenter_p[1] > -1.001) {
surface_id_val[i] = master;
}
}
}
/// contact declaration
Contact * contact = Contact::newContact(my_model,
_ct_rigid,
_cst_expli,
_cnst_regular_grid);
ContactRigid * my_contact = dynamic_cast<ContactRigid *>(contact);
my_contact->initContact(false);
my_contact->addMasterSurface(master);
my_contact->addImpactorSurfaceToMasterSurface(impactor, master);
UniqueConstantFricCoef * fric_coef = new UniqueConstantFricCoef(*my_contact, master, 0.3);
//my_contact->setFrictionCoefficient(fric_coef);
my_model.updateCurrentPosition(); // neighbor structure uses current position for init
my_contact->initNeighborStructure(master);
my_contact->initSearch(); // does nothing so far
// boundary conditions
Vector<UInt> * top_nodes = new Vector<UInt>(0, 1);
Real * coordinates = my_mesh.getNodes().values;
Real * displacement = my_model.getDisplacement().values;
bool * boundary = my_model.getBoundary().values;
UInt * surface_to_nodes_offset = my_contact->getSurfaceToNodesOffset().values;
UInt * surface_to_nodes = my_contact->getSurfaceToNodes().values;
// symetry boundary conditions
for(UInt n = surface_to_nodes_offset[impactor]; n < surface_to_nodes_offset[impactor+1]; ++n) {
UInt node = surface_to_nodes[n];
Real y_coord = coordinates[node*dim + 1];
if (y_coord > -0.00001) {
boundary[node*dim + 1] = true;
top_nodes->push_back(node);
}
}
// ground boundary conditions
for(UInt n = surface_to_nodes_offset[rigid_body_surface]; n < surface_to_nodes_offset[rigid_body_surface+1]; ++n) {
UInt node = surface_to_nodes[n];
Real y_coord = coordinates[node*dim + 1];
if (y_coord < -1.49)
boundary[node*dim] = true;
boundary[node*dim + 1] = true;
}
UInt * top_nodes_val = top_nodes->values;
my_model.updateResidual();
#ifdef AKANTU_USE_IOHELPER
/// initialize the paraview output
DumperParaview dumper;
dumper.SetMode(TEXT);
dumper.SetPoints(my_model.getFEM().getMesh().getNodes().values, dim, nb_nodes, "coord_sliding_cube_2d");
dumper.SetConnectivity((int *)my_model.getFEM().getMesh().getConnectivity(element_type).values,
paraview_type, nb_element, C_MODE);
dumper.AddNodeDataField(my_model.getDisplacement().values,
dim, "displacements");
dumper.AddNodeDataField(my_model.getVelocity().values, dim, "velocity");
dumper.AddNodeDataField(my_model.getResidual().values, dim, "force");
dumper.AddNodeDataField(my_model.getForce().values, dim, "applied_force");
dumper.AddElemDataField(my_model.getMaterial(0).getStrain(element_type).values, dim*dim, "strain");
dumper.AddElemDataField(my_model.getMaterial(0).getStress(element_type).values, dim*dim, "stress");
dumper.SetEmbeddedValue("displacements", 1);
dumper.SetEmbeddedValue("applied_force", 1);
dumper.SetPrefix("paraview/sliding_cube_2d/");
dumper.Init();
dumper.Dump();
#endif //AKANTU_USE_IOHELPER
std::ofstream out_info;
out_info.open("output_files/sliding_cube_2d.csv");
out_info << "%id,ftop,fcont,zone,stickNode,contNode" << std::endl;
std::ofstream energy;
energy.open("output_files/sliding_cube_2d_energy.csv");
energy << "%id,kin,pot,tot" << std::endl;
Real * current_position = my_model.getCurrentPosition().values;
/* ------------------------------------------------------------------------ */
/* Main loop */
/* ------------------------------------------------------------------------ */
for(UInt s = 1; s <= max_steps; ++s) {
if(s % 10 == 0) {
std::cout << "passing step " << s << "/" << max_steps << "\r";
std::cout.flush();
}
if(s % 20000 == 0){
my_model.updateCurrentPosition();
my_contact->updateContact();
}
// impose normal displacement
if(s <= imposing_steps) {
Real current_displacement = max_displacement/(static_cast<Real>(imposing_steps))*s;
for(UInt n=0; n<top_nodes->getSize(); ++n) {
UInt node = top_nodes_val[n];
displacement[node*dim + 1] = current_displacement;
}
}
// damp velocity in order to find equilibrium
if(s > imposing_steps && s < imposing_steps+damping_steps && s%damping_interval == 0) {
for (UInt i=0; i < nb_nodes; ++i) {
for (UInt j=0; j < dim; ++j)
velocity_val[i*dim + j] *= damping_ratio;
}
}
// give initial velocity
if(s == imposing_steps+damping_steps) {
ContactRigid::SurfaceToImpactInfoMap::const_iterator it_imp;
it_imp = my_contact->getImpactorsInformation().find(master);
ContactRigid::ImpactorInformationPerMaster * imp_info = it_imp->second;
bool * stick = imp_info->node_is_sticking->values;
Real * p_vel = imp_info->previous_velocities->values;
for(UInt i=0; i < imp_info->active_impactor_nodes->getSize(); ++i) {
stick[i*2] = false;
stick[i*2+1] = false;
p_vel[i*dim + 0] = imposed_velocity;
}
/*for (UInt i=0; i < nb_nodes; ++i) {
if(coordinates[i*dim + 1] > -1) {
velocity_val[i*dim] = imposed_velocity;
}
}*/
UInt * connectivity = my_mesh.getConnectivity(element_type).values;
UInt nb_nodes_elem = Mesh::getNbNodesPerElement(element_type);
for(UInt i=0; i < nb_element; ++i) {
Real barycenter[dim];
Real * barycenter_p = &barycenter[0];
my_mesh.getBarycenter(i,element_type,barycenter_p);
if(barycenter_p[1] > -1) {
for (UInt j=0; j < nb_nodes_elem; ++j) {
velocity_val[connectivity[i*nb_nodes_elem+j]*dim] = imposed_velocity;
acceleration_val[connectivity[i*nb_nodes_elem +j]*dim] = 0.;
}
}
}
}
my_model.explicitPred();
my_model.initializeUpdateResidualData();
my_contact->solveContact();
my_model.updateResidual(false);
my_contact->avoidAdhesion();
my_contact->frictionPredictor();
// find the total force applied at the imposed displacement surface (top)
Real * residual = my_model.getResidual().values;
Real top_force = 0.;
for(UInt n=0; n<top_nodes->getSize(); ++n) {
UInt node = top_nodes_val[n];
top_force += residual[node*dim + 1];
}
// find index of master surface in impactors_information
ContactRigid::SurfaceToImpactInfoMap::const_iterator it_imp;
it_imp = my_contact->getImpactorsInformation().find(master);
// find the total contact force and contact area
ContactRigid::ImpactorInformationPerMaster * imp_info = it_imp->second;
UInt * active_imp_nodes_val = imp_info->active_impactor_nodes->values;
Real contact_force = 0.;
Real contact_zone = 0.;
for (UInt i = 0; i < imp_info->active_impactor_nodes->getSize(); ++i) {
UInt node = active_imp_nodes_val[i];
contact_force += residual[node*dim + 1];
contact_zone = std::max(contact_zone, current_position[node*dim]);
}
out_info << s << "," << top_force << "," << contact_force << "," << contact_zone << ",";
// test if correct result is found
if((s == max_steps) && (std::abs(contact_zone - 1.8988) > 1e-4)) {
std::cout << "sliding distance = " << contact_zone << " but should be = 1.8988" << std::endl;
return EXIT_FAILURE;
}
my_model.updateAcceleration();
const Vector<bool> * sticking_nodes = imp_info->node_is_sticking;
bool * sticking_nodes_val = sticking_nodes->values;
UInt nb_sticking_nodes = 0;
for (UInt i = 0; i < imp_info->active_impactor_nodes->getSize(); ++i) {
if(sticking_nodes_val[i*2])
nb_sticking_nodes++;
}
out_info << nb_sticking_nodes << "," << imp_info->active_impactor_nodes->getSize() << std::endl;
my_model.explicitCorr();
my_contact->frictionCorrector();
Real epot = my_model.getPotentialEnergy();
Real ekin = my_model.getKineticEnergy();
energy << s << "," << ekin << "," << epot << "," << ekin+epot << std::endl;
#ifdef AKANTU_USE_IOHELPER
if(s % 100 == 0) dumper.Dump();
#endif //AKANTU_USE_IOHELPER
}
out_info.close();
energy.close();
delete fric_coef;
delete my_contact;
finalize();
return EXIT_SUCCESS;
}

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