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material_igfem_iterative_stiffness_reduction.cc
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material_igfem_iterative_stiffness_reduction.cc
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/**
* @file material_igfem_iterative_stiffness_reduction.cc
* @author Aurelia Isabel Cuba Ramos <aurelia.cubaramos@epfl.ch>
* @date Thu Mar 10 08:37:43 2016
*
* @brief Implementation of igfem material iterative stiffness reduction
*
*
* 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_igfem_iterative_stiffness_reduction.hh"
#include <math.h>
namespace akantu {
template <Int spatial_dimension>
/* -------------------------------------------------------------------------- */
MaterialIGFEMIterativeStiffnessReduction<spatial_dimension>::
MaterialIGFEMIterativeStiffnessReduction(SolidMechanicsModel & model,
const ID & id)
: Material(model, id), MaterialIGFEMSawToothDamage<spatial_dimension>(model,
id),
eps_u("ultimate_strain", *this), reduction_step("damage_step", *this),
D("tangent", *this), Gf(0.), crack_band_width(0.), max_reductions(0),
reduction_constant(0.) {
AKANTU_DEBUG_IN();
this->eps_u.initialize(1);
this->D.initialize(1);
this->reduction_step.initialize(1);
this->internals_to_transfer.push_back("ultimate_strain");
this->internals_to_transfer.push_back("tangent");
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
template <Int dim>
void MaterialIGFEMIterativeStiffnessReduction<dim>::initMaterial() {
AKANTU_DEBUG_IN();
MaterialIGFEMSawToothDamage<dim>::initMaterial();
/// get the parameters for the sub-material that can be damaged
ID mat_name = this->sub_material_names[1];
const Material & mat = this->model->getMaterial(mat_name);
this->crack_band_width = mat.getParam<Real>("crack_band_width");
this->max_reductions = mat.getParam<UInt>("max_reductions");
this->reduction_constant = mat.getParam<Real>("reduction_constant");
this->Gf = mat.getParam<Real>("Gf");
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
template <Int spatial_dimension>
void MaterialIGFEMIterativeStiffnessReduction<spatial_dimension>::
computeNormalizedEquivalentStress(const Array<Real> & grad_u,
ElementType el_type,
GhostType ghost_type) {
AKANTU_DEBUG_IN();
/// storage for the current stress
Matrix<Real> sigma(spatial_dimension, spatial_dimension);
/// Vector to store eigenvalues of current stress tensor
Vector<Real> eigenvalues(spatial_dimension);
/// iterators on the needed internal fields
Array<Real>::const_scalar_iterator Sc_it =
this->Sc(el_type, ghost_type).begin();
Array<Real>::scalar_iterator dam_it =
this->damage(el_type, ghost_type).begin();
Array<Real>::scalar_iterator equivalent_stress_it =
this->equivalent_stress(el_type, ghost_type).begin();
Array<Real>::const_matrix_iterator grad_u_it =
grad_u.begin(spatial_dimension, spatial_dimension);
Array<Real>::const_matrix_iterator grad_u_end =
grad_u.end(spatial_dimension, spatial_dimension);
Real * mu_ptr = this->mu(el_type, ghost_type).data();
Real * lambda_ptr = this->lambda(el_type, ghost_type).data();
/// loop over all the quadrature points and compute the equivalent stress
for (; grad_u_it != grad_u_end; ++grad_u_it) {
/// compute the stress
sigma.zero();
MaterialIGFEMElastic<spatial_dimension>::computeStressOnQuad(
*grad_u_it, sigma, *lambda_ptr, *mu_ptr);
MaterialIGFEMSawToothDamage<
spatial_dimension>::computeDamageAndStressOnQuad(sigma, *dam_it);
/// compute eigenvalues
sigma.eig(eigenvalues);
/// find max eigenvalue and normalize by tensile strength
*equivalent_stress_it =
*(std::max_element(eigenvalues.data(),
eigenvalues.data() + spatial_dimension)) /
(*Sc_it);
++Sc_it;
++equivalent_stress_it;
++dam_it;
++lambda_ptr;
++mu_ptr;
}
AKANTU_DEBUG_OUT();
}
/* -------------------------------------------------------------------------- */
template <Int spatial_dimension>
UInt MaterialIGFEMIterativeStiffnessReduction<
spatial_dimension>::updateDamage() {
UInt nb_damaged_elements = 0;
if (this->norm_max_equivalent_stress >= 1.) {
AKANTU_DEBUG_IN();
/// update the damage only on non-ghosts elements! Doesn't make sense to
/// update on ghost.
GhostType ghost_type = _not_ghost;
;
Mesh::type_iterator it = this->model->getFEEngine().getMesh().firstType(
spatial_dimension, ghost_type, _ek_igfem);
Mesh::type_iterator last_type =
this->model->getFEEngine().getMesh().lastType(spatial_dimension,
ghost_type, _ek_igfem);
/// get the Young's modulus of the damageable sub-material
ID mat_name = this->sub_material_names[1];
Real E = this->model->getMaterial(mat_name).template getParam<Real>("E");
/// loop over all the elements
for (; it != last_type; ++it) {
ElementType el_type = *it;
/// get iterators on the needed internal fields
const Array<Idx> & sub_mat = this->sub_material(el_type, ghost_type);
Array<Idx>::const_scalar_iterator sub_mat_it = sub_mat.begin();
Array<Real>::const_scalar_iterator equivalent_stress_it =
this->equivalent_stress(el_type, ghost_type).begin();
Array<Real>::const_scalar_iterator equivalent_stress_end =
this->equivalent_stress(el_type, ghost_type).end();
Array<Real>::scalar_iterator dam_it =
this->damage(el_type, ghost_type).begin();
Array<Idx>::scalar_iterator reduction_it =
this->reduction_step(el_type, ghost_type).begin();
Array<Real>::const_scalar_iterator eps_u_it =
this->eps_u(el_type, ghost_type).begin();
Array<Real>::scalar_iterator Sc_it =
this->Sc(el_type, ghost_type).begin();
Array<Real>::const_scalar_iterator D_it =
this->D(el_type, ghost_type).begin();
/// loop over all the elements of the given type
UInt nb_element = this->element_filter(el_type, ghost_type).getSize();
UInt nb_quads = this->fem->getNbIntegrationPoints(el_type, ghost_type);
bool damage_element = false;
for (Int e = 0; e < nb_element; ++e) {
damage_element = false;
/// check if damage occurs in the element
for (Int q = 0; q < nb_quads;
++q, ++reduction_it, ++sub_mat_it, ++equivalent_stress_it) {
if (*equivalent_stress_it >= (1 - this->dam_tolerance) *
this->norm_max_equivalent_stress &&
*sub_mat_it != 0) {
/// check if this element can still be damaged
if (*reduction_it == this->max_reductions)
continue;
damage_element = true;
}
}
if (damage_element) {
/// damage the element
nb_damaged_elements += 1;
sub_mat_it -= nb_quads;
reduction_it -= nb_quads;
for (Int q = 0; q < nb_quads; ++q) {
if (*sub_mat_it) {
/// increment the counter of stiffness reduction steps
*reduction_it += 1;
if (*reduction_it == this->max_reductions)
*dam_it = this->max_damage;
else {
/// update the damage on this quad
*dam_it = 1. - (1. / std::pow(this->reduction_constant,
*reduction_it));
/// update the stiffness on this quad
*Sc_it = (*eps_u_it) * (1. - (*dam_it)) * E * (*D_it) /
((1. - (*dam_it)) * E + (*D_it));
}
}
++sub_mat_it;
++dam_it;
++reduction_it;
++eps_u_it;
++Sc_it;
++D_it;
}
} else {
dam_it += nb_quads;
eps_u_it += nb_quads;
Sc_it += nb_quads;
D_it += nb_quads;
}
}
}
}
StaticCommunicator & comm =
akantu::StaticCommunicator::getStaticCommunicator();
comm.allReduce(&nb_damaged_elements, 1, _so_sum);
AKANTU_DEBUG_OUT();
return nb_damaged_elements;
}
/* -------------------------------------------------------------------------- */
template <Int spatial_dimension>
void MaterialIGFEMIterativeStiffnessReduction<
spatial_dimension>::onElementsAdded(__attribute__((unused))
const Array<Element> & element_list,
__attribute__((unused))
const NewElementsEvent & event) {
MaterialIGFEMSawToothDamage<spatial_dimension>::onElementsAdded(element_list,
event);
/// set the correct damage iteration step (is UInt->cannot be interpolated)
Real val = 0.;
for (ghost_type_t::iterator g = ghost_type_t::begin();
g != ghost_type_t::end(); ++g) {
GhostType ghost_type = *g;
/// loop over all types in the material
typedef ElementTypeMapArray<Idx>::type_iterator iterator;
iterator it = this->element_filter.firstType(spatial_dimension, ghost_type,
_ek_igfem);
iterator last_type =
this->element_filter.lastType(spatial_dimension, ghost_type, _ek_igfem);
/// loop over all types in the filter
for (; it != last_type; ++it) {
const ElementType el_type = *it;
Array<Real>::scalar_iterator dam_it =
this->damage(el_type, ghost_type).begin();
Array<Idx>::scalar_iterator reduction_it =
this->reduction_step(el_type, ghost_type).begin();
UInt nb_element = this->element_filter(el_type, ghost_type).getSize();
UInt nb_quads = this->fem->getNbIntegrationPoints(el_type);
UInt * sub_mat_ptr = this->sub_material(el_type, ghost_type).data();
for (Int q = 0; q < nb_element * nb_quads;
++q, ++sub_mat_ptr, ++dam_it, ++reduction_it) {
if (*sub_mat_ptr) {
if (Math::are_float_equal(*dam_it, this->max_damage))
*reduction_it = this->max_reductions;
else {
for (Int i = 0; i < this->max_reductions; ++i) {
val = 1 - (1. / std::pow(this->reduction_constant, i));
if (Math::are_float_equal(val, *dam_it))
*reduction_it = i;
}
}
}
}
}
}
}
/* -------------------------------------------------------------------------- */
INSTANTIATE_MATERIAL(MaterialIGFEMIterativeStiffnessReduction);
} // namespace akantu

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