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test_explicit_friction.cc
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test_explicit_friction.cc
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/**
* @file test_explicit_friction.cc
*
* @author Mohit Pundir <mohit.pundir@epfl.ch>
*
* @date creation: Sun Jun 06 2021
* @date last modification: Sun Jun 06 2021
*
* @brief Test contact mechanics with friction
*
*
* @section LICENSE
*
* Copyright (©) 2018-2021 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_mechanics_model.hh"
#include "coupler_solid_contact.hh"
#include "non_linear_solver.hh"
#include "solid_mechanics_model.hh"
#include "surface_selector.hh"
/* -------------------------------------------------------------------------- */
using namespace akantu;
/* -------------------------------------------------------------------------- */
template <typename T> std::vector<T> arrange(T start, T stop, T step = 1) {
std::vector<T> values;
for (T value = start; value <= stop; value += step)
values.push_back(value);
return values;
}
int main(int argc, char * argv[]) {
UInt max_normal_steps = 2500;
UInt max_shear_steps = 7500;
Real max_shear_displacement = 1e-1;
Real max_normal_displacement = 2e-2;
Real damping_ratio = 0.99;
std::string mesh_file = "sliding-block-2D.msh";
std::string material_file = "material-friction.dat";
const UInt spatial_dimension = 2;
initialize(material_file, argc, argv);
Mesh mesh(spatial_dimension);
mesh.read(mesh_file);
CouplerSolidContact coupler(mesh);
auto & solid = coupler.getSolidMechanicsModel();
auto & contact = coupler.getContactMechanicsModel();
auto && material_selector =
std::make_shared<MeshDataMaterialSelector<std::string>>("physical_names",
solid);
solid.setMaterialSelector(material_selector);
coupler.initFull(_analysis_method = _explicit_lumped_mass);
auto && surface_selector = std::make_shared<PhysicalSurfaceSelector>(mesh);
contact.getContactDetector().setSurfaceSelector(surface_selector);
solid.applyBC(BC::Dirichlet::FixedValue(0.0, _x), "lower");
solid.applyBC(BC::Dirichlet::FixedValue(0.0, _y), "lower");
Real time_step = solid.getStableTimeStep();
time_step *= 0.05;
coupler.setTimeStep(time_step);
std::cout << "Stable time increment : " << time_step << " sec "
<< std::endl;
coupler.setBaseName("explicit-friction");
coupler.addDumpFieldVector("displacement");
coupler.addDumpFieldVector("normals");
coupler.addDumpFieldVector("contact_force");
coupler.addDumpFieldVector("tangential_force");
coupler.addDumpFieldVector("external_force");
coupler.addDumpFieldVector("internal_force");
coupler.addDumpField("gaps");
coupler.addDumpField("areas");
coupler.addDumpField("blocked_dofs");
coupler.addDumpField("strain");
coupler.addDumpField("stress");
coupler.addDumpField("contact_state");
auto & velocity = solid.getVelocity();
auto & gaps = contact.getGaps();
auto xi = arrange<Real>(0, 1, 1. / max_shear_steps);
std::vector<Real> shear_displacements;
std::transform(xi.begin(), xi.end(), std::back_inserter(shear_displacements),
[&](Real & p) -> Real {
return 0. + (max_shear_displacement)*pow(p, 3) *
(10 - 15 * p + 6 * pow(p, 2));
});
auto normal_xi = arrange<Real>(0, 1, 1. / max_normal_steps);
std::vector<Real> normal_displacements;
std::transform(normal_xi.begin(), normal_xi.end(),
std::back_inserter(normal_displacements),
[&](Real & p) -> Real {
return 0. + (max_normal_displacement)*pow(p, 3) *
(10 - 15 * p + 6 * pow(p, 2));
});
auto max_steps = max_normal_steps + max_shear_steps;
auto & contact_nodes = surface_selector->getSlaveList();
auto & tangential_traction = contact.getTangentialTractions();
for (UInt s : arange(max_steps)) {
if (s < max_normal_steps) {
solid.applyBC(BC::Dirichlet::FixedValue(-normal_displacements[s], _y),
"loading");
} else {
solid.applyBC(BC::Dirichlet::FixedValue(
shear_displacements[s - max_normal_steps], _x),
"loading");
}
coupler.solveStep();
for (auto && tuple : zip(gaps, make_view(velocity, spatial_dimension))) {
auto & gap = std::get<0>(tuple);
auto & vel = std::get<1>(tuple);
if (gap > 0) {
vel *= damping_ratio;
}
}
if (s % 100 == 0) {
coupler.dump();
}
auto sum = std::accumulate(tangential_traction.begin(),
tangential_traction.end(), 0.0);
auto num_tang_traction = std::abs(sum) / contact_nodes.size();
Real exp_tang_traction = 0.3 * 1.4e6;
Real error =
std::abs(num_tang_traction - exp_tang_traction) / exp_tang_traction;
if (error > 1e-3 and num_tang_traction > exp_tang_traction) {
std::cerr << error << "----" << num_tang_traction << std::endl;
return EXIT_FAILURE;
}
}
coupler.dump();
finalize();
return EXIT_SUCCESS;
}

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