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test_material_viscoelastic_maxwell_relaxation.cc
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Fri, May 10, 08:30

test_material_viscoelastic_maxwell_relaxation.cc
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/**
* @file test_material_viscoelastic_maxwell_relaxation.cc
*
* @author Emil Gallyamov <emil.gallyamov@epfl.ch>
*
* @date creation: Thu May 17 2018
* @date last modification:
*
* @brief test of the viscoelastic material: relaxation
*
* @section LICENSE
*
* Copyright (©) 2010-2018 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 <fstream>
#include <iostream>
#include <limits>
#include <sstream>
/* -------------------------------------------------------------------------- */
#include "material_viscoelastic_maxwell.hh"
#include "non_linear_solver.hh"
#include "solid_mechanics_model.hh"
#include "sparse_matrix.hh"
using namespace akantu;
/* -------------------------------------------------------------------------- */
/* Main */
/* -------------------------------------------------------------------------- */
int main(int argc, char * argv[]) {
akantu::initialize("material_viscoelastic_maxwell.dat", argc, argv);
// sim data
Real eps = 0.1;
const UInt dim = 2;
Real sim_time = 100.;
Real T = 10.;
Real tolerance = 1e-6;
Mesh mesh(dim);
mesh.read("test_material_viscoelastic_maxwell.msh");
const ElementType element_type = _quadrangle_4;
SolidMechanicsModel model(mesh);
/* ------------------------------------------------------------------------ */
/* Initialization */
/* ------------------------------------------------------------------------ */
model.initFull(_analysis_method = _static);
std::cout << model.getMaterial(0) << std::endl;
std::stringstream filename_sstr;
filename_sstr << "test_material_viscoelastic_maxwell.out";
std::ofstream output_data;
output_data.open(filename_sstr.str().c_str());
Material & mat = model.getMaterial(0);
const Array<Real> & stress = mat.getStress(element_type);
Vector<Real> Eta = mat.get("Eta");
Vector<Real> Ev = mat.get("Ev");
Real Einf = mat.get("Einf");
Real nu = mat.get("nu");
Real lambda = Eta(0) / Ev(0);
Real pre_mult = 1 / (1 + nu) / (1 - 2 * nu);
Real time_step = 0.1;
UInt nb_nodes = mesh.getNbNodes();
const Array<Real> & coordinate = mesh.getNodes();
Array<Real> & displacement = model.getDisplacement();
Array<bool> & blocked = model.getBlockedDOFs();
/// Setting time step
model.setTimeStep(time_step);
UInt max_steps = sim_time / time_step + 1;
Real time = 0.;
auto & solver = model.getNonLinearSolver();
solver.set("max_iterations", 200);
solver.set("threshold", 1e-7);
solver.set("convergence_type", SolveConvergenceCriteria::_residual);
/* ------------------------------------------------------------------------ */
/* Main loop */
/* ------------------------------------------------------------------------ */
for (UInt s = 0; s <= max_steps; ++s) {
std::cout << "Time Step = " << time_step << "s" << std::endl;
std::cout << "Time = " << time << std::endl;
// impose displacement
Real epsilon = 0;
if (time < T) {
epsilon = eps * time / T;
} else {
epsilon = eps;
}
for (UInt n = 0; n < nb_nodes; ++n) {
if (Math::are_float_equal(coordinate(n, 0), 0.0)) {
displacement(n, 0) = 0;
blocked(n, 0) = true;
displacement(n, 1) = epsilon * coordinate(n, 1);
blocked(n, 1) = true;
} else if (Math::are_float_equal(coordinate(n, 1), 0.0)) {
displacement(n, 0) = epsilon * coordinate(n, 0);
blocked(n, 0) = true;
displacement(n, 1) = 0;
blocked(n, 1) = true;
} else if (Math::are_float_equal(coordinate(n, 0), 0.001)) {
displacement(n, 0) = epsilon * coordinate(n, 0);
blocked(n, 0) = true;
displacement(n, 1) = epsilon * coordinate(n, 1);
blocked(n, 1) = true;
} else if (Math::are_float_equal(coordinate(n, 1), 0.001)) {
displacement(n, 0) = epsilon * coordinate(n, 0);
blocked(n, 0) = true;
displacement(n, 1) = epsilon * coordinate(n, 1);
blocked(n, 1) = true;
}
}
try {
model.solveStep();
} catch (debug::Exception & e) {
}
Int nb_iter = solver.get("nb_iterations");
Real error = solver.get("error");
bool converged = solver.get("converged");
if (converged) {
std::cout << "Converged in " << nb_iter << " iterations" << std::endl;
} else {
std::cout << "Didn't converge after " << nb_iter
<< " iterations. Error is " << error << std::endl;
return EXIT_FAILURE;
}
// analytical solution
Real solution_11 = 0.;
if (time < T) {
solution_11 = pre_mult * eps / T *
(Einf * time + lambda * Ev(0) * (1 - exp(-time / lambda)));
} else {
solution_11 =
pre_mult * eps *
(Einf + lambda * Ev(0) / T *
(exp((T - time) / lambda) - exp(-time / lambda)));
}
// data output
output_data << s * time_step << " " << epsilon << " " << solution_11;
Array<Real>::const_matrix_iterator stress_it = stress.begin(dim, dim);
Array<Real>::const_matrix_iterator stress_end = stress.end(dim, dim);
for (; stress_it != stress_end; ++stress_it) {
output_data << " " << (*stress_it)(0, 0);
// test error
Real rel_error_11 =
std::abs(((*stress_it)(0, 0) - solution_11) / solution_11);
if (rel_error_11 > tolerance) {
std::cerr << "Relative error: " << rel_error_11 << std::endl;
return EXIT_FAILURE;
}
}
output_data << std::endl;
time += time_step;
}
output_data.close();
finalize();
std::cout << "Test successful!" << std::endl;
return EXIT_SUCCESS;
}

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