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material_linear_isotropic_hardening_inline_impl.cc
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material_linear_isotropic_hardening_inline_impl.cc
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/**
* @file material_linear_isotropic_hardening.cc
*
* @author Ramin Aghababaei <ramin.aghababaei@epfl.ch>
* @author Daniel Pino Munoz <daniel.pinomunoz@epfl.ch>
* @author Lucas Frerot <lucas.frerot@epfl.ch>
*
* @date Tue Jul 09 18:15:37 20130
*
* @brief Implementation of the inline functions of the material plasticity
*
* @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 "material_linear_isotropic_hardening.hh"
/* -------------------------------------------------------------------------- */
/* -------------------------------------------------------------------------- */
template<UInt dim>
inline void
MaterialLinearIsotropicHardening<dim>::computeStressOnQuad(const Matrix<Real> & grad_u,
const Matrix<Real> & previous_grad_u,
Matrix<Real> & sigma,
const Matrix<Real> & previous_sigma,
Matrix<Real> & inelastic_strain,
const Matrix<Real> & previous_inelastic_strain,
Real & iso_hardening,
const Real & previous_iso_hardening,
const Real & sigma_th,
const Real & previous_sigma_th) {
//Infinitesimal plasticity
//Real r=iso_hardening;
Real dp=0.0;
Real d_dp=0.0;
UInt n=0;
Real delta_sigma_th = sigma_th - previous_sigma_th;
Matrix<Real> grad_delta_u(grad_u);
grad_delta_u -= previous_grad_u;
//Compute trial stress, sigma_tr
Matrix<Real> sigma_tr(dim, dim);
MaterialElastic<dim>::computeStressOnQuad(grad_delta_u, sigma_tr, delta_sigma_th);
sigma_tr += previous_sigma;
// Compute deviatoric trial stress, sigma_tr_dev
Matrix<Real> sigma_tr_dev(sigma_tr);
sigma_tr_dev -= Matrix<Real>::eye(dim, sigma_tr.trace() / 3.0);
// Compute effective deviatoric trial stress
Real s = sigma_tr_dev.doubleDot(sigma_tr_dev);
Real sigma_tr_dev_eff = std::sqrt(3./2. * s);
const Real iso_hardening_t = previous_iso_hardening;
//Loop for correcting stress based on yield function
while ((sigma_tr_dev_eff - iso_hardening - this->sigma_y) > 0) {
d_dp = (sigma_tr_dev_eff - 3. * this->mu *dp - iso_hardening - this->sigma_y)
/ (3. * this->mu + this->h);
//r = r + h * dp;
iso_hardening = iso_hardening_t + this->h * d_dp;
dp = dp + d_dp;
++n;
/// TODO : explicit this criterion with an error message
if ((d_dp < 1e-5) || (n>50))
break;
}
//Update internal variable
Matrix<Real> delta_inelastic_strain(dim, dim, 0.);
if (std::abs(sigma_tr_dev_eff) >
sigma_tr_dev.norm<L_inf>() * Math::getTolerance()) {
delta_inelastic_strain.copy(sigma_tr_dev);
delta_inelastic_strain *= 3./2. * dp / sigma_tr_dev_eff;
}
MaterialPlastic<dim>::computeStressAndInelasticStrainOnQuad(grad_delta_u, sigma, previous_sigma,
inelastic_strain, previous_inelastic_strain,
delta_inelastic_strain);
}
/* -------------------------------------------------------------------------- */
template<UInt dim>
inline void
MaterialLinearIsotropicHardening<dim>::computeTangentModuliOnQuad(Matrix<Real> & tangent,
const Matrix<Real> & grad_u,
const Matrix<Real> & previous_grad_u,
const Matrix<Real> & sigma_tensor,
const Matrix<Real> & previous_sigma_tensor,
const Real & iso_hardening) const {
// Real r=iso_hardening;
// Matrix<Real> grad_delta_u(grad_u);
// grad_delta_u -= previous_grad_u;
// //Compute trial stress, sigma_tr
// Matrix<Real> sigma_tr(dim, dim);
// MaterialElastic<dim>::computeStressOnQuad(grad_delta_u, sigma_tr);
// sigma_tr += previous_sigma_tensor;
// // Compute deviatoric trial stress, sigma_tr_dev
// Matrix<Real> sigma_tr_dev(sigma_tr);
// sigma_tr_dev -= Matrix<Real>::eye(dim, sigma_tr.trace() / 3.0);
// // Compute effective deviatoric trial stress
// Real s = sigma_tr_dev.doubleDot(sigma_tr_dev);
// Real sigma_tr_dev_eff=std::sqrt(3./2. * s);
// // Compute deviatoric stress, sigma_dev
// Matrix<Real> sigma_dev(sigma_tensor);
// sigma_dev -= Matrix<Real>::eye(dim, sigma_tensor.trace() / 3.0);
// // Compute effective deviatoric stress
// s = sigma_dev.doubleDot(sigma_dev);
// Real sigma_dev_eff = std::sqrt(3./2. * s);
// Real xr = 0.0;
// if(sigma_tr_dev_eff > sigma_dev_eff * Math::getTolerance())
// xr = sigma_dev_eff / sigma_tr_dev_eff;
// Real __attribute__((unused)) q = 1.5 * (1. / (1. + 3. * this->mu / this->h) - xr);
UInt cols = tangent.cols();
UInt rows = tangent.rows();
for (UInt m = 0; m < rows; ++m) {
UInt i = VoigtHelper<dim>::vec[m][0];
UInt j = VoigtHelper<dim>::vec[m][1];
for (UInt n = 0; n < cols; ++n) {
UInt k = VoigtHelper<dim>::vec[n][0];
UInt l = VoigtHelper<dim>::vec[n][1];
// This section of the code is commented
// There were some problems with the convergence of plastic-coupled simulations with thermal expansion
// XXX: DO NOT REMOVE
/*if (((sigma_tr_dev_eff-iso_hardening-sigmay) > 0) && (xr > 0)) {
tangent(m,n) =
2. * this->mu * q * (sigma_tr_dev (i,j) / sigma_tr_dev_eff) * (sigma_tr_dev (k,l) / sigma_tr_dev_eff) +
(i==k) * (j==l) * 2. * this->mu * xr +
(i==j) * (k==l) * (this->kpa - 2./3. * this->mu * xr);
if ((m == n) && (m>=dim))
tangent(m, n) = tangent(m, n) - this->mu * xr;
} else {*/
tangent(m,n) = (i==k) * (j==l) * 2. * this->mu +
(i==j) * (k==l) * this->lambda;
tangent(m,n) -= (m==n) * (m>=dim) * this->mu;
//}
//correct tangent stiffness for shear component
}
}
}

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