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material_iterative_stiffness_reduction.cc
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rAKA akantu
material_iterative_stiffness_reduction.cc
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/**
* @file material_iterative_stiffness_reduction.cc
* @author Aurelia Isabel Cuba Ramos <aurelia.cubaramos@epfl.ch>
* @date Thu Feb 18 16:03:56 2016
*
* @brief Implementation of material iterative stiffness reduction
*
* @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_iterative_stiffness_reduction.hh"
#include "communicator.hh"
#include "solid_mechanics_model_RVE.hh"
/* -------------------------------------------------------------------------- */
namespace
akantu
{
/* -------------------------------------------------------------------------- */
template
<
UInt
spatial_dimension
>
MaterialIterativeStiffnessReduction
<
spatial_dimension
>::
MaterialIterativeStiffnessReduction
(
SolidMechanicsModel
&
model
,
const
ID
&
id
)
:
MaterialDamageIterative
<
spatial_dimension
>
(
model
,
id
),
eps_u
(
"ultimate_strain"
,
*
this
),
D
(
"tangent"
,
*
this
),
Gf
(
0.
),
crack_band_width
(
0.
),
reduction_constant
(
0.
)
{
AKANTU_DEBUG_IN
();
this
->
registerParam
(
"Gf"
,
Gf
,
_pat_parsable
|
_pat_modifiable
,
"fracture energy"
);
this
->
registerParam
(
"crack_band_width"
,
crack_band_width
,
_pat_parsable
|
_pat_modifiable
,
"crack_band_width"
);
this
->
registerParam
(
"reduction_constant"
,
reduction_constant
,
2.
,
_pat_parsable
|
_pat_modifiable
,
"reduction constant"
);
this
->
eps_u
.
initialize
(
1
);
this
->
D
.
initialize
(
1
);
AKANTU_DEBUG_OUT
();
}
/* -------------------------------------------------------------------------- */
template
<
UInt
spatial_dimension
>
void
MaterialIterativeStiffnessReduction
<
spatial_dimension
>::
initMaterial
()
{
AKANTU_DEBUG_IN
();
MaterialDamageIterative
<
spatial_dimension
>::
initMaterial
();
for
(
auto
ghost_type
:
ghost_types
)
{
/// loop over all types in the filter
for
(
auto
&
el_type
:
this
->
element_filter
.
elementTypes
(
_ghost_type
=
ghost_type
))
{
/// get the stiffness on each quad point
auto
Sc_it
=
this
->
Sc
(
el_type
,
ghost_type
).
begin
();
/// get the tangent of the tensile softening on each quad point
auto
D_it
=
this
->
D
(
el_type
,
ghost_type
).
begin
();
auto
D_end
=
this
->
D
(
el_type
,
ghost_type
).
end
();
/// get the ultimate strain on each quad
auto
eps_u_it
=
this
->
eps_u
(
el_type
,
ghost_type
).
begin
();
// compute the tangent and the ultimate strain for each quad
for
(;
D_it
!=
D_end
;
++
Sc_it
,
++
D_it
,
++
eps_u_it
)
{
*
eps_u_it
=
((
2.
*
this
->
Gf
)
/
(
*
Sc_it
*
this
->
crack_band_width
));
*
D_it
=
*
(
Sc_it
)
/
((
*
eps_u_it
)
-
((
*
Sc_it
)
/
this
->
E
));
}
}
}
AKANTU_DEBUG_OUT
();
}
/* -------------------------------------------------------------------------- */
template
<
UInt
spatial_dimension
>
void
MaterialIterativeStiffnessReduction
<
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
auto
Sc_it
=
this
->
Sc
(
el_type
,
ghost_type
).
begin
();
auto
dam_it
=
this
->
damage
(
el_type
,
ghost_type
).
begin
();
auto
equivalent_stress_it
=
this
->
equivalent_stress
(
el_type
,
ghost_type
).
begin
();
auto
grad_u_it
=
grad_u
.
begin
(
spatial_dimension
,
spatial_dimension
);
auto
grad_u_end
=
grad_u
.
end
(
spatial_dimension
,
spatial_dimension
);
/// 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
.
clear
();
MaterialElastic
<
spatial_dimension
>::
computeStressOnQuad
(
*
grad_u_it
,
sigma
,
0.
);
MaterialDamageIterative
<
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
.
storage
(),
eigenvalues
.
storage
()
+
spatial_dimension
))
/
(
*
Sc_it
);
++
Sc_it
;
++
equivalent_stress_it
;
++
dam_it
;
}
AKANTU_DEBUG_OUT
();
}
/* -------------------------------------------------------------------------- */
template
<
UInt
spatial_dimension
>
UInt
MaterialIterativeStiffnessReduction
<
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
);
Mesh
::
type_iterator
last_type
=
this
->
model
.
getFEEngine
().
getMesh
().
lastType
(
spatial_dimension
,
ghost_type
);
/// loop over all the elements
for
(;
it
!=
last_type
;
++
it
)
{
ElementType
el_type
=
*
it
;
/// get iterators on the needed internal fields
auto
equivalent_stress_it
=
this
->
equivalent_stress
(
el_type
,
ghost_type
).
begin
();
auto
equivalent_stress_end
=
this
->
equivalent_stress
(
el_type
,
ghost_type
).
end
();
auto
dam_it
=
this
->
damage
(
el_type
,
ghost_type
).
begin
();
auto
reduction_it
=
this
->
reduction_step
(
el_type
,
ghost_type
).
begin
();
auto
eps_u_it
=
this
->
eps_u
(
el_type
,
ghost_type
).
begin
();
auto
Sc_it
=
this
->
Sc
(
el_type
,
ghost_type
).
begin
();
auto
D_it
=
this
->
D
(
el_type
,
ghost_type
).
begin
();
/// loop over all the quads of the given element type
for
(;
equivalent_stress_it
!=
equivalent_stress_end
;
++
equivalent_stress_it
,
++
dam_it
,
++
reduction_it
,
++
eps_u_it
,
++
Sc_it
,
++
D_it
)
{
/// check if damage occurs
if
(
*
equivalent_stress_it
>=
(
1
-
this
->
dam_tolerance
)
*
this
->
norm_max_equivalent_stress
)
{
/// check if this element can still be damaged
if
(
*
reduction_it
==
this
->
max_reductions
)
continue
;
/// 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
))
*
this
->
E
*
(
*
D_it
)
/
((
1.
-
(
*
dam_it
))
*
this
->
E
+
(
*
D_it
));
}
nb_damaged_elements
+=
1
;
}
}
}
}
auto
rve_model
=
dynamic_cast
<
SolidMechanicsModelRVE
*>
(
&
this
->
model
);
if
(
rve_model
==
NULL
)
{
const
auto
&
comm
=
this
->
model
.
getMesh
().
getCommunicator
();
comm
.
allReduce
(
nb_damaged_elements
,
SynchronizerOperation
::
_sum
);
}
AKANTU_DEBUG_OUT
();
return
nb_damaged_elements
;
}
/* -------------------------------------------------------------------------- */
INSTANTIATE_MATERIAL
(
iterative_stiffness_reduction
,
MaterialIterativeStiffnessReduction
);
}
// namespace akantu
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