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rAKA/test/test_model/test_solid_mechanics_model/test_materials/test_material_viscoelastic/test_material_standard_linear_solid_deviatoric_relaxation_tension.cc
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test_material_standard_linear_solid_deviatoric_relaxation_tension.cc
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/**
* @file test_material_standard_linear_solid_deviatoric_relaxation_tension.cc
*
* @author David Simon Kammer <david.kammer@epfl.ch>
* @author Nicolas Richart <nicolas.richart@epfl.ch>
*
* @date creation: Mon Aug 09 2010
* @date last modification: Sun Oct 19 2014
*
* @brief test of the viscoelastic material: relaxation
*
* @section LICENSE
*
* Copyright (©) 2010-2012, 2014, 2015 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 <limits>
#include <fstream>
#include <sstream>
#include <iostream>
/* -------------------------------------------------------------------------- */
#include "solid_mechanics_model.hh"
using namespace akantu;
int main(int argc, char *argv[])
{
akantu::initialize("material_standard_linear_solid_deviatoric_relaxation.dat", argc, argv);
// sim data
Real T = 10.;
Real eps = 0.001;
// const UInt dim = 3;
const UInt dim = 2;
Real sim_time = 25.;
//Real sim_time = 250.;
Real time_factor = 0.1;
Real tolerance = 1e-5;
Mesh mesh(dim);
mesh.read("test_material_standard_linear_solid_deviatoric_relaxation.msh");
// mesh_io.read("hexa_structured.msh",mesh);
//const ElementType element_type = _hexahedron_8;
const ElementType element_type = _quadrangle_4;
SolidMechanicsModel model(mesh);
/* ------------------------------------------------------------------------ */
/* Initialization */
/* ------------------------------------------------------------------------ */
model.initFull();
std::cout << model.getMaterial(0) << std::endl;
model.assembleMassLumped();
model.updateResidual();
model.getMaterial(0).setToSteadyState();
std::stringstream filename_sstr;
filename_sstr << "test_material_standard_linear_solid_deviatoric_relaxation_tension.out";
std::ofstream output_data;
output_data.open(filename_sstr.str().c_str());
output_data << "#[1]-time [2]-sigma_analytic [3+]-sigma_measurements" << std::endl;
Material & mat = model.getMaterial(0);
const Array<Real> & stress = mat.getStress(element_type);
Real Eta = mat.getParam<Real>("Eta");
Real EV = mat.getParam<Real>("Ev");
Real Einf = mat.getParam<Real>("Einf");
Real E0 = mat.getParam<Real>("E");
Real kpa = mat.getParam<Real>("kapa");
Real mu = mat.getParam<Real>("mu");
Real gamma = EV/E0;
Real gammainf = Einf/E0;
Real tau = Eta / EV;
std::cout << "relaxation time = " << tau << std::endl;
UInt nb_nodes = mesh.getNbNodes();
const Array<Real> & coordinate = mesh.getNodes();
Array<Real> & displacement = model.getDisplacement();
/// Setting time step
Real time_step = model.getStableTimeStep() * time_factor;
std::cout << "Time Step = " << time_step << "s" << std::endl;
model.setTimeStep(time_step);
UInt max_steps = sim_time / time_step;
UInt out_interval = 1;
Real time = 0.;
/* ------------------------------------------------------------------------ */
/* Main loop */
/* ------------------------------------------------------------------------ */
for(UInt s = 0; s <= max_steps; ++s) {
if(s % 1000 == 0)
std::cerr << "passing step " << s << "/" << max_steps << std::endl;
time = s * time_step;
// impose displacement
Real epsilon = 0.;
if (time < T) {
epsilon = eps * time / T;
}
else {
epsilon = eps;
}
for (UInt n=0; n<nb_nodes; ++n) {
for (UInt d=0; d<dim; ++d)
displacement(n,d) = epsilon * coordinate(n,d);
}
// compute stress
model.updateResidual();
// print output
if(s % out_interval == 0) {
// analytical solution
Real epskk = dim * eps;
Real solution= 0.;
if (time < T) {
solution = 2 * mu * (eps - epskk/3.) / T * (gammainf * time + gamma * tau * (1 - exp(-time/tau))) + gammainf * kpa * epskk * time / T;
}
else {
solution = 2 * mu * (eps - epskk/3.) * (gammainf + gamma * tau / T *(exp((T-time)/tau) - exp(-time/tau))) + gammainf * kpa * epskk;
}
output_data << s*time_step << " " << solution;
// data output
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)(1,1);
// test error
Real rel_error_1 = std::abs(((*stress_it)(1,1) - solution) / solution);
if (rel_error_1 > tolerance) {
std::cerr << "Relative error: " << rel_error_1 << std::endl;
return EXIT_FAILURE;
}
}
output_data << std::endl;
}
}
finalize();
std::cout << "Test successful!" << std::endl;
return EXIT_SUCCESS;
}
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