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Code_Aster
®
Version
7.4
Titrate:
Operator
AFFE_CHAR_MECA_C
Date:
31/01/05
Author (S):
X. DESROCHES
Key
:
U4.44.05-E
Page
:
1/8
Instruction manual
U4.4- booklet: Modeling
HT-66/05/004/A
Organization (S):
EDF-R & D/AMA














Instruction manual
U4.4- booklet: Modeling
Document: U4.44.05



Operator
AFFE_CHAR_MECA_C








1 Goal
To affect loadings and boundary conditions mechanical of complex type.
This operator supplements the operators
AFFE_CHAR_MECA
and
AFFE_CHAR_MECA_F
[U4.44.01] which
allow to affect loadings and boundary conditions mechanical of real type.
This operator must be used, at the time of a harmonic study (operator
DYNA_LINE_HARM
[U4.53.11]),
to impose different dephasings, either between each element of the model, or between
various degrees of freedom within the same element.
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Code_Aster
®
Version
7.4
Titrate:
Operator
AFFE_CHAR_MECA_C
Date:
31/01/05
Author (S):
X. DESROCHES
Key
:
U4.44.05-E
Page
:
2/8
Instruction manual
U4.4- booklet: Modeling
HT-66/05/004/A
2 Syntax
general

CH [char_meca] = AFFE_CHAR_MECA_C
(
MODELE= Mo,
[model]
|
DDL_IMPO = _F
(see
key word DDL_IMPO
[
§ 3.4
])
|
LIAISON_DDL = _F (see
key word LIAISON_DDL [
§ 3.5
])
|
FORCE_POUTRE = _F
(see key word FORCE_POUTRE [
§ 3.6
])
INFORMATION
=
/
1,
[DEFECT]
/2,

VERI_DDL
=/
“YES”,
[DEFECT]
/“NOT”,

)
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Code_Aster
®
Version
7.4
Titrate:
Operator
AFFE_CHAR_MECA_C
Date:
31/01/05
Author (S):
X. DESROCHES
Key
:
U4.44.05-E
Page
:
3/8
Instruction manual
U4.4- booklet: Modeling
HT-66/05/004/A
3 Operands
3.1
General information on the operands
3.1.1 Two categories of operands
The operands under a key word factor are of two forms:
·
operands specifying the geometrical entities on which are affected them
loadings (key words
GROUP_NO
,
GROUP_MA
, etc…),
·
operands specifying the affected values (
DX
,
DY
, etc…). Arguments of these
operands all are of the complex type.
This is true near with an exception: the argument of
COEF_MULT
for the key word factor
LIAISON_DDL
is obligatorily of real type.

3.1.2 Designation of the topological entities of assignment of the loadings
In a general way, the entities on which values must be affected are defined:
·
on all the mesh by the operand
ALL = “YES”
·
by node and in this case:
- is by the operand
GROUP_NO
allowing to introduce a list of groups of
nodes,
-
maybe by the operand
NODE
allowing to introduce a list of nodes.
·
by mesh and in this case:
- is
by
GROUP_MA
allowing to introduce a list of groups of meshs,
- is
by
NET
allowing to introduce a list of meshs.

3.1.3 Regulate of overload
To define the field of assignment most simply possible, the rule of overload is used
defined in the document “Course of a study with Aster '':
it is the last assignment which precedes.

3.2 Operand
MODEL
MODEL
= Mo
Concept produced by the operator
AFFE_MODELE
[U4.41.01] where the types of elements are defined
stop affected on the mesh.
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Code_Aster
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Version
7.4
Titrate:
Operator
AFFE_CHAR_MECA_C
Date:
31/01/05
Author (S):
X. DESROCHES
Key
:
U4.44.05-E
Page
:
4/8
Instruction manual
U4.4- booklet: Modeling
HT-66/05/004/A
3.3 Operand
INFORMATION
INFORMATION
=
Level of the impressions on the file
“MESSAGE”
1
: nothing
2
: nothing

3.4 Word
key
DDL_IMPO

3.4.1 Drank
Key word factor usable to impose, with nodes or groups of nodes or nodes of
meshs or of groups of meshs, one or more values of displacement (or some
associated sizes).

3.4.2 Syntax
|
DDL_IMPO
=
_F
(
/
TOUT=
“YES”,
/
|
NOEUD=
lno
, [l_noeud]
|
GROUP_NO=
lgno,
[l_gr_noeud]
|
GROUP_MA=
lgma,
[l_gr_maille]
|
NET =
my, [l_maille]
|
DX=
ux,
[C]
|
DY=
uy,
[C]
|
DZ=
zu,
[C]
|
DRX=
theta
_x, [C]
|
DRY=
theta
_y, [C]
|
DRZ=
theta
_z, [C]
|
GRX= G,
[C]
|
PRES=
p,
[C]
|
PHI=
phi
, [C]
)
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Code_Aster
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Version
7.4
Titrate:
Operator
AFFE_CHAR_MECA_C
Date:
31/01/05
Author (S):
X. DESROCHES
Key
:
U4.44.05-E
Page
:
5/8
Instruction manual
U4.4- booklet: Modeling
HT-66/05/004/A
3.4.3 Operands: choice of the degree of freedom
| DDL_IMPO
All the specified values are defined in the TOTAL reference mark of definition of the mesh.
DX = ux
DY = uy
DZ = uz
Value of the component of displacement in imposed translation
on the specified nodes
Only if the specified nodes belong to discrete elements of
translation - rotation and of beam:
DRX =
theta_x
DRY =
theta_y
DRZ =
theta_z
Value of the component of displacement in rotation imposed on
specified nodes
Only if the specified nodes belong to elements of beam
“POU_D_TG”:
GRX = G
Value of the roll of the beam
Only if the specified nodes belong to elements fluid or fluid structure:
PRES= p
Acoustic pressure in the fluid (modeling
“3d_FLUIDE”
)
PHI=
phi
Potential of displacements of the fluid (modelings
“3d_FLUIDE”
and
“FLUI_STRU”
)
Only if the specified nodes belong to elements of free face:
DZ = uz
Imposed displacement of the free face (modeling
“2d_FLUI_PESA”)
PHI =
phi
Potential of displacements of the fluid (modeling
“2d_FLUI_PESA”)

3.4.4 Checks and recommendations
It is checked that it
ddl
specified exists in this node for the elements affected in
MODEL
with
meshs which contain the node.
However, if the same boundary condition is specified twice by two calls to
AFFE_CHAR_MECA_C
(for example, with two values of imposed displacement), that led to one
singular matrix.
If it is specified twice (or more) in only one call to
AFFE_CHAR_MECA_C
, the rule of
overload applies and a message of alarm (indicating the overload) is transmitted.
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Code_Aster
®
Version
7.4
Titrate:
Operator
AFFE_CHAR_MECA_C
Date:
31/01/05
Author (S):
X. DESROCHES
Key
:
U4.44.05-E
Page
:
6/8
Instruction manual
U4.4- booklet: Modeling
HT-66/05/004/A
3.5 Word
key
LIAISON_DDL
3.5.1 Drank
Key word factor usable to define a linear relation between degrees of freedom of two or
several nodes.
3.5.2 Syntax
LIAISON_DDL = _F
(
/
NODE
= lno, [l_noeud]
/
GROUP_NO
= lgno,
[l_gr_noeud]
DDL=
|
“DX”,
|
“DY”,
|
“DZ”,
|
“DRX”,
|
“DRY”,
|
“DRZ”,
|
COEF_MULT
=
alphai,
[l_R]
COEF_IMPO
=
beta,
[C]
)
3.5.3 Operands
GROUP_NO
or
NODE
: list nodes
(
)
NR I
R
I
= 1,
ordinate in a natural way:
·
in the order of the list of groups of nodes, and for each group of nodes,
in the order of definition of the group by
GROUP_NO
,
·
in the order of the list of nodes for
NODE
.
DDL
: list
ddl
(
)
U I
R
I
= 1,
of
R
texts taken among:
“DX”,
“DY”,
“DZ”,
“DRX”,
“DRY”,
“DRZ”
COEF_MULT
: list
(
)
alpha I
R
I
= 1,
coefficients of the real type.
COEF_IMPO
: coefficient
beta
of complex type.
The following kinematic condition will be applied:
alpha U
beta
I
I
I
R
=
=
1
3.5.4 Precautions
of use
3.5.4.1 Components in rotation
Components of displacement in rotation
DRX, DRY, DRZ
can intervene only in
combinations only assigned to nodes which belong to elements
discrete or of beam (see
DDL_IMPO
).

3.5.4.2 Linear relation between the ddl of the same node
In this particular case, one will repeat behind the key word
NODE
the name of the node as many time as it
y has
ddl
in the relation. Example: to impose
U
U
X
y
=
on the N1 node, one will write:
LIAISON_DDL = _F
(NODE
= (“N1”, “N1”),
DDL
=
(“DX”
“DY”),
COEF_MULT
=
(1., - 1.),
COEF_IMPO
=
(IH
0., 0.),
)
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Code_Aster
®
Version
7.4
Titrate:
Operator
AFFE_CHAR_MECA_C
Date:
31/01/05
Author (S):
X. DESROCHES
Key
:
U4.44.05-E
Page
:
7/8
Instruction manual
U4.4- booklet: Modeling
HT-66/05/004/A

3.5.4.3 Linear relation between groups of nodes
It is important to note that with an occurrence of the key word factor
LIAISON_DDL
one corresponds and
only one linear relation.
If one wants to impose the same relation between 2 groups of nodes
GRN01
and
GRN02
(even
displacement
U
X
node with node for example) one cannot write:
LIAISON_DDL = _F
(GROUP_NO = (“GRNO1”, “GRNO2”),
DDL
=
(“DX”,
“DX”),
COEF_MULT
=
(1.,
- 1.),
COEF_IMPO
=
(IH
0., 0.) ,
)
This writing has direction only if
GRNO1
and
GRNO2
contain each one one node. It
will be necessary in the case to above clarify each linear relation, node by node.

3.6 Word
key
FORCE_POUTRE
3.6.1 Drank
Key word factor usable to apply linear forces, to elements of the beam type
(
POU_D_T_
,
POU_D_E
,
) definite on all the mesh or one or more meshs or of the groups
meshs. The forces are definite component by component, that is to say in the reference mark
TOTAL
, that is to say
in the local reference mark of the element defined by the operator
AFFE_CARA_ELEM
[U4.42.01].
3.6.2 Syntax
FORCE_POUTRE
=_F
(
/
ALL
=
“YES”,
/
|
NET
=
lma, [l_maille]
|
GROUP_MA
=
lgma,
[l_gr_maille]
/
|
FX
=
fx,
[C]
|
FY
=
fy,
[C]
|
FZ
=
fz,
[C]
/
|
NR
=
N,
[C]
|
VY
=
vy,
[C]
|
VZ
=
vz,
[C]
TYPE_CHARGE
=
/
“FORCE”, [DEFECT]
/
“WIND”
)
3.6.3 Operands: forces
/
| fx
:
Force according to
X
[C]
| fy
:
Force according to
Y
[C]
| fz
:
Force according to
Z
[C]
/
| N:
Effort of traction and compression
[C]
| vy
:
Following transverse effort
Y
[C]
| vz
:
Following transverse effort
Z
[C]
Let us note that one must remain homogeneous in each occurrence of the key word factor
FORCE_POUTRE
: that is to say all the components are defined in the reference mark
TOTAL
that is to say all them
components are defined in the reference mark of definition of the beam.
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Code_Aster
®
Version
7.4
Titrate:
Operator
AFFE_CHAR_MECA_C
Date:
31/01/05
Author (S):
X. DESROCHES
Key
:
U4.44.05-E
Page
:
8/8
Instruction manual
U4.4- booklet: Modeling
HT-66/05/004/A
3.6.4 Modelings and meshs
This loading applies to the types of meshs and following modelings:
Net Modélisation
SEG2 POU_D_T,
POU_C_T,
POU_D_E
This loading is not currently available for modeling
POU_D_TG
.
3.6.5 Operand
TYPE_CHARGE
TYPE_CHARGE
=
/
'
FORCE
',
/
'
WIND
',
If the excitation exerted on the element of beam is due to the wind, it is then regarded as
following.

3.7 Operand
VERI_DDL
VERI_DDL
=/
'
YES
',
/
'
NOT
',
Checking which DDLs specified exist well with the specified nodes of the elements affected in
the model.