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test_single_spring_friction_vel_weak_exp.cc
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test_single_spring_friction_vel_weak_exp.cc
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/**
* @file test_single_spring_friction_vel_weak_exp.cc
* @author David Kammer <david.kammer@epfl.ch>
* @date Mon Oct 17 16:18:55 2011
*
* @brief test friction of exponential velocity weakening law (not with analytical solution)
*
* @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 <stdio.h>
#include <stdlib.h>
#ifdef AKANTU_USE_IOHELPER
#include <io_helper.hh>
using namespace iohelper;
#endif //AKANTU_USE_IOHELPER
#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 "velocity_weakening_coulomb.hh"
#include "velocity_weakening_exponential.hh"
#include "contact_neighbor_structure.hh"
#include "regular_grid_neighbor_structure.hh"
#include "contact_search.hh"
#include "contact_search_explicit.hh"
using namespace akantu;
/* -------------------------------------------------------------------------- */
Surface impactor = 0;
Surface master = 1;
UInt the_node = 0;
const ElementType element_type = _triangle_3;
#ifdef AKANTU_USE_IOHELPER
const ElemType paraview_type = TRIANGLE1;
#endif //AKANTU_USE_IOHELPER
const char* mesh_name = "single_triangle.msh";
const char* folder_name = "single_spring_friction_vel_weak_exp";
std::string result_name;
Real mu_s = 0.3;
Real mu_d = 0.2;
Real power = 1.;
const UInt paraview_dump_int = 1e1;
const UInt file_dump_int = 1e1;
const UInt max_steps = 1e6;
const UInt stick_stop = 3;
Real n_k = 0.15;
Real normal_force;
Real start_displacement = 0.2;
Mesh * mesh;
SolidMechanicsModel * model;
UInt spatial_dimension = 2;
Real time_step_security = 3.;
Real time_step;
UInt nb_nodes;
UInt nb_elements;
UInt stick_counter = 0;
bool patch_test = false;
const Real tolerance = std::numeric_limits<Real>::epsilon() * 10.;
// variables of model
Real * coordinates;
Real * displacement;
Real * current_position;
Real * velocity;
Real * residual;
Real * acceleration;
bool * boundary;
Real * force;
Real * mass;
std::map < std::string, VectorBase* > restart_map;
#ifdef AKANTU_USE_IOHELPER
void paraviewInit(Dumper & dumper);
#endif //AKANTU_USE_IOHELPER
void loadRestartInformation(ContactRigid * contact);
void printPredictor(UInt step,
std::ofstream & out_stream);
void printCorrector(UInt step,
ContactRigid * contact,
std::ofstream & out_stream);
void getStickInfo(ContactRigid * contact);
bool testFloat(Real a, Real b, Real adm_error);
/* -------------------------------------------------------------------------- */
Int main(int argc, char *argv[])
{
akantu::initialize(argc, argv);
debug::setDebugLevel(dblWarning);
// 1: name
// 2: initial displacement
// 3: static friction coefficient
// 4: dynamic friction coefficient
// 5: power
// 6: ratio N/K with N normal force & K stiffness
if (argc == 7) {
result_name = argv[1];
start_displacement = atof(argv[2]);
mu_s = atof(argv[3]);
mu_d = atof(argv[4]);
power = atof(argv[5]);
n_k = atof(argv[6]);
}
else {
result_name = "patch_test_output";
patch_test = true;
// return EXIT_FAILURE;
}
/// load mesh
mesh = new Mesh(spatial_dimension);
MeshIOMSH mesh_io;
mesh_io.read(mesh_name, *mesh);
/// build facet connectivity and surface id
MeshUtils::buildFacets(*mesh,1,0);
MeshUtils::buildSurfaceID(*mesh);
/// declaration of model
model = new SolidMechanicsModel(*mesh);
nb_nodes = model->getFEM().getMesh().getNbNodes();
nb_elements = model->getFEM().getMesh().getNbElement(element_type);
std::cout << "Nb nodes : " << nb_nodes << " - nb elements : " << nb_elements << std::endl;
/// model initialization
model->initVectors();
// initialize the vectors
model->getForce().clear();
model->getVelocity().clear();
model->getAcceleration().clear();
model->getDisplacement().clear();
model->initExplicit();
model->initModel();
/// read and initialize material
model->readMaterials("material.dat");
model->initMaterials();
Real stable_time_step = model->getStableTimeStep();
time_step = stable_time_step/time_step_security;
model->setTimeStep(time_step);
std::cout << "The time step is " << time_step << std::endl;
// accessors to model elements
coordinates = mesh->getNodes().values;
displacement = model->getDisplacement().values;
velocity = model->getVelocity().values;
acceleration = model->getAcceleration().values;
boundary = model->getBoundary().values;
residual = model->getResidual().values;
model->updateCurrentPosition();
current_position = model->getCurrentPosition().values;
force = model->getForce().values;
mass = model->getMass().values;
model->assembleMassLumped();
UInt nb_surfaces = mesh->getNbSurfaces();
nb_surfaces += 1;
/// contact declaration
Contact * contact_structure = Contact::newContact(*model,
_ct_rigid,
_cst_expli,
_cnst_regular_grid);
ContactRigid * contact = dynamic_cast<ContactRigid *>(contact_structure);
//contact->initContact(false);
contact->addMasterSurface(master);
contact->addImpactorSurfaceToMasterSurface(impactor, master);
/// define the friction law
FrictionCoefficient *fric_coef;
fric_coef = new VelocityWeakeningExponential(*contact, master, mu_s, mu_d, power);
// load restart file
loadRestartInformation(contact);
// set boundary condition
displacement[the_node*spatial_dimension] = start_displacement;
model->updateCurrentPosition();
model->updateResidual();
Real stiffness = std::abs(residual[the_node * spatial_dimension] / start_displacement);
normal_force = n_k * stiffness;
force[the_node*spatial_dimension+1] = -normal_force;
if (start_displacement > tolerance) {
std::cout << "Start displacement = " << start_displacement << " ; Residual = " << residual[the_node*spatial_dimension] << " -> Stiffness K = " << stiffness << std::endl;
std::cout << "Mass = " << mass[the_node] << std::endl;
}
else
std::cout << "No start displacement!! " << std::endl;
/// initialize the paraview output
#ifdef AKANTU_USE_IOHELPER
DumperParaview dumper;
#endif //AKANTU_USE_IOHELPER
std::ofstream out_info;
if (!patch_test) {
model->updateResidual();
#ifdef AKANTU_USE_IOHELPER
paraviewInit(dumper);
#endif //AKANTU_USE_IOHELPER
/// output files
std::stringstream name_info;
name_info << "output_files/" << folder_name << "/global_info.dat";
out_info.open(name_info.str().c_str());
out_info << "%id time fnorm fres ffric ftot mu disp vel stick ekin epot etot" << std::endl;
}
UInt step = 0;
Real previous_vel = 0.;
UInt count_cycle = 0;
/* ------------------------------------------------------------------------ */
/* Main loop */
/* ------------------------------------------------------------------------ */
while(stick_counter <= stick_stop && step <= max_steps) {
// increase step
step += 1;
if(step % 1000 == 0) {
std::cout << "passing step " << step << "/" << max_steps << "\r";
std::cout.flush();
}
model->explicitPred();
model->updateResidual();
if (step % file_dump_int == 0 && !patch_test)
printPredictor(step, out_info);
contact->frictionPredictor();
model->updateAcceleration();
model->explicitCorr();
contact->frictionCorrector();
// see if node sticks
getStickInfo(contact);
// count numbers of cycles
if (Math::are_float_equal(velocity[the_node * spatial_dimension], 0.) &&
!Math::are_float_equal(previous_vel, 0.))
count_cycle++;
previous_vel = velocity[the_node * spatial_dimension];
if(step % file_dump_int == 0 && !patch_test)
printCorrector(step, contact, out_info);
#ifdef AKANTU_USE_IOHELPER
if(step % paraview_dump_int == 0 && !patch_test) dumper.Dump();
#endif //AKANTU_USE_IOHELPER
}
std::cout << "passing step " << step << "/" << max_steps << std::endl;
Real final_displacement = displacement[the_node * spatial_dimension];
// check patch test
if(patch_test) {
Real correct_final_disp = -0.0200196;
Real admissible_error = 1e-07;
UInt correct_nb_cycle = 3;
//if (!(Math::are_float_equal(final_displacement, correct_final_disp)) | !(count_cycle == correct_nb_cycle)) {
if (!(testFloat(final_displacement, correct_final_disp, admissible_error)) | !(count_cycle == correct_nb_cycle)) {
std::cout << "Final displacement is " << final_displacement << ", which should be " << correct_final_disp << std::endl;
std::cout << "Final number of cycles is " << count_cycle << ", which should be " << correct_nb_cycle << std::endl;
return EXIT_FAILURE;
}
else {
std::cout << "Patch test successful!" << std::endl;
return EXIT_SUCCESS;
}
}
else {
/// output files
std::stringstream result_name_path;
result_name_path << "output_files/" << folder_name << "/" << result_name << ".dat";
std::ofstream out_result;
out_result.open(result_name_path.str().c_str(), std::ios::app);
if (!out_result.good()) {
std::cout << "Could not open result file " << std::endl;
return EXIT_FAILURE;
}
out_result << start_displacement << " " << final_displacement << " " << count_cycle << std::endl;
out_result.close();
}
out_info.close();
delete fric_coef;
delete contact;
delete model;
delete mesh;
finalize();
return EXIT_SUCCESS;
}
/* -------------------------------------------------------------------------- */
#ifdef AKANTU_USE_IOHELPER
void paraviewInit(Dumper & dumper) {
std::stringstream name;
name << "paraview/" << folder_name << "/";
dumper.SetMode(TEXT);
dumper.SetPoints(model->getFEM().getMesh().getNodes().values,
spatial_dimension, nb_nodes, "coordinates");
dumper.SetConnectivity((int *)model->getFEM().getMesh().getConnectivity(element_type).values,
paraview_type, nb_elements, C_MODE);
dumper.AddNodeDataField(model->getDisplacement().values,
spatial_dimension, "displacements");
dumper.AddNodeDataField(model->getVelocity().values,
spatial_dimension, "velocity");
dumper.AddNodeDataField(model->getResidual().values,
spatial_dimension, "force");
dumper.AddNodeDataField(model->getMass().values,
1, "mass");
dumper.AddNodeDataField(model->getForce().values,
spatial_dimension, "applied_force");
dumper.AddElemDataField(model->getMaterial(0).getStrain(element_type).values,
spatial_dimension*spatial_dimension, "strain");
dumper.AddElemDataField(model->getMaterial(0).getStress(element_type).values,
spatial_dimension*spatial_dimension, "stress");
dumper.SetEmbeddedValue("displacements", 1);
dumper.SetEmbeddedValue("applied_force", 1);
dumper.SetPrefix(name.str().c_str());
dumper.Init();
dumper.Dump();
}
#endif //AKANTU_USE_IOHELPER
/* -------------------------------------------------------------------------- */
void loadRestartInformation(ContactRigid * contact) {
// boundary conditions
Vector<bool> * boundary_r = new Vector<bool>(nb_nodes, spatial_dimension, false);
// sticked nodes
(*boundary_r)(1,0) = true; (*boundary_r)(1,1) = true;
(*boundary_r)(2,0) = true; (*boundary_r)(2,1) = true;
// the impactor node
(*boundary_r)(0,1) = true;
memcpy(boundary, boundary_r->values, spatial_dimension*nb_nodes*sizeof(bool));
// set the active impactor node
Vector<bool> * ai_nodes = new Vector<bool>(nb_nodes, 1, false);
(*ai_nodes)(the_node) = true;
restart_map["active_impactor_nodes"] = ai_nodes;
// not defined master type, because won't use solve contact
Vector<ElementType> * et_nodes = new Vector<ElementType>(nb_nodes, 1, _not_defined);
restart_map["master_element_type"] = et_nodes;
// master normal x=0; y=1
Vector<Real> * mn_nodes = new Vector<Real>(0, spatial_dimension);
Real normal[spatial_dimension];
normal[0] = 0.; normal[1] = 1.;
mn_nodes->push_back(normal);
restart_map["master_normals"] = mn_nodes;
// node is sticking
Vector<bool> * is_nodes = new Vector<bool>(nb_nodes, 2, false);
(*is_nodes)(0,0) = true;
(*is_nodes)(0,1) = true;
restart_map["node_is_sticking"] = is_nodes;
// no friction force
Vector<Real> * ff_nodes = new Vector<Real>(0, spatial_dimension);
Real force[spatial_dimension];
force[0] = 0.; force[1] = 0.;
ff_nodes->push_back(force);
restart_map["friction_forces"] = ff_nodes;
// the original stick position (for regularized friction)
Vector<Real> * sp_nodes = new Vector<Real>(0, spatial_dimension);
Real position[spatial_dimension];
position[0] = 0.;
position[1] = 0.;
sp_nodes->push_back(position);
restart_map["stick_positions"] = sp_nodes;
// no residual forces
Vector<Real> * rf_nodes = new Vector<Real>(0, spatial_dimension);
Real r_force[spatial_dimension];
r_force[0] = 0.; r_force[1] = 0.;
rf_nodes->push_back(r_force);
restart_map["residual_forces"] = rf_nodes;
// no previous velocities
Vector<Real> * pv_nodes = new Vector<Real>(0, spatial_dimension);
Real vel[spatial_dimension];
vel[0] = 0.; vel[1] = 0.;
pv_nodes->push_back(vel);
restart_map["previous_velocities"] = pv_nodes;
contact->setRestartInformation(restart_map, master);
delete boundary_r;
delete ai_nodes;
delete et_nodes;
delete mn_nodes;
delete is_nodes;
delete ff_nodes;
delete sp_nodes;
delete rf_nodes;
delete pv_nodes;
}
/* -------------------------------------------------------------------------- */
void printPredictor(UInt step, std::ofstream & out_stream) {
out_stream << step << " " << step*time_step << " " << residual[the_node*spatial_dimension + 1] << " " << residual[the_node * spatial_dimension];
}
/* -------------------------------------------------------------------------- */
void printCorrector(UInt step, ContactRigid * contact, std::ofstream & out_stream) {
Real epot = model->getPotentialEnergy();
Real ekin = model->getKineticEnergy();
// find index of master surface in impactors_information
ContactRigid::SurfaceToImpactInfoMap::const_iterator it_imp;
it_imp = contact->getImpactorsInformation().find(master);
// find the total contact force and contact area
ContactRigid::ImpactorInformationPerMaster * imp_info = it_imp->second;
Real * friction_forces_val = imp_info->friction_forces->values;
bool * sticking_nodes_val = imp_info->node_is_sticking->values;
out_stream << " " << friction_forces_val[0] << " " << residual[the_node * spatial_dimension] << " " << friction_forces_val[0] / residual[the_node * spatial_dimension + 1] << " " << displacement[the_node * spatial_dimension] << " " << velocity[the_node * spatial_dimension] << " " << sticking_nodes_val[0] << " " << ekin << " " << epot << " " << ekin+epot << std::endl;
if (sticking_nodes_val[0])
stick_counter++;
else
stick_counter = 0;
}
/* -------------------------------------------------------------------------- */
void getStickInfo(ContactRigid * contact) {
// find index of master surface in impactors_information
ContactRigid::SurfaceToImpactInfoMap::const_iterator it_imp;
it_imp = contact->getImpactorsInformation().find(master);
// find the total contact force and contact area
ContactRigid::ImpactorInformationPerMaster * imp_info = it_imp->second;
bool * sticking_nodes_val = imp_info->node_is_sticking->values;
if (sticking_nodes_val[the_node*2])
stick_counter++;
else
stick_counter = 0;
}
/* -------------------------------------------------------------------------- */
bool testFloat(Real a, Real b, Real adm_error) {
if (fabs(a-b) < adm_error)
return true;
else
return false;
}

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