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
Organization (S): EDF-R & D/AMA
Handbook of Utilization
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 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.
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/05/004/A
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
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])
INFO
=
/
1,
[DEFAUT]
/2,
VERI_DDL
=/
“OUI”,
[DEFAUT]
/“NON”,
)
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/05/004/A
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
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 grid by the operand TOUT = “OUI”
·
by node and in this case:
- is by operand GROUP_NO allowing to introduce a list of groups of
nodes,
-
maybe by operand NOEUD 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
MAILLE 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 “Déroulement of a study with Aster '':
it is the last assignment which precedes.
3.2 Operand
MODELE
MODELE
= Mo
Concept produced by operator AFFE_MODELE [U4.41.01] where the types of elements are defined
stop affected on the grid.
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/05/004/A
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
: 4/8
3.3 Operand
INFO
INFO
=
Level of the impressions on 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=
“OUI”,
/ | NOEUD=
lno
, [l_noeud]
| GROUP_NO=
lgno,
[l_gr_noeud]
| GROUP_MA=
lgma,
[l_gr_maille]
|
MAILLE =
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]
)
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/05/004/A
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
: 5/8
3.4.3 Operands: choice of the degree of freedom
| DDL_IMPO
All the specified values are defined in reference mark GLOBAL of definition of the grid.
DX = ux
Value of the component of displacement in imposed translation
DY = uy
on the specified nodes
DZ = uz
Only if the specified nodes belong to discrete elements of
translation - rotation and of beam:
DRX = theta_x
Value of the component of displacement in rotation imposed on
DRY = theta_y
specified nodes
DRZ = theta_z
Only if the specified nodes belong to elements of beam “POU_D_TG”:
GRX = G
Value of the warping 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 the specified ddl exists in this node for the elements affected in the MODELE to
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.
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/05/004/A
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
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 (
/
NOEUD
= 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 NOEUD: list nodes NR (I
R
I
= 1,) ordered 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 NOEUD.
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,) of coefficients of the real type.
COEF_IMPO: coefficient beta of the complex type.
R
The following kinematic condition will be applied: alpha U = beta
I
I
I =1
3.5.4 Precautions
of use
3.5.4.1 Components in rotation
The 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 as many repeat behind key word NOEUD the name of the node time as it
y has ddl in the relation. Example: to impose U = U
X
y on the node N1, one will write:
LIAISON_DDL = _F (NODE
= (“N1”, “N1”),
DDL
=
(“DX”
“DY”),
COEF_MULT
=
(1., - 1.),
COEF_IMPO
=
(IH
0., 0.),
)
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/05/004/A
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
3.5.4.3 Linear relation between groups of nodes
It is important to note that to 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 Ux 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,…) defined on all the grid or one or more meshs or of the groups
meshs. The forces are definite component by component, either in reference mark GLOBAL, or
in the local reference mark of the element defined by operator AFFE_CARA_ELEM [U4.42.01].
3.6.2 Syntax
FORCE_POUTRE
=_F
(
/
TOUT
=
“OUI”,
/ | MAILLE
=
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]
/
“VENT”
)
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: either all the components are defined in reference mark GLOBAL or all them
components are defined in the reference mark of definition of the beam.
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/05/004/A
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
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”,
/“VENT”,
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
=/“OUI”,
/“NON”,
Checking which DDLs specified exist well with the specified nodes of the elements affected in
the model.
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/05/004/A
Outline document