Code_Aster ®
Version
7.4
Titrate:
Operator CALC_FORC_AJOU


Date:
19/01/05
Author (S):
NR. GREFFET, G. DEVESA, D. NUNEZ Key
:
U4.66.03-B Page
: 1/6

Organization (S): EDF-R & D/AMA, CS IF

Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
Document: U4.66.03

Operator CALC_FORC_AJOU

1 Goal

This command makes it possible to calculate the effect of hydrodynamic overpressure due to the movement
of drive of the structure in seismic analysis where one breaks up the total movement into
movement of drive and relative movement. The calculation of this force is carried out like that of
mass added by analogy thermal, but instead of taking into account only the movement
relative, one obtains a force added to the second member, also projected on the modes of
structure without the fluid, to take into account the movement of drive.

The calculation of the masses added [R4.07.03] by CALC_MATR_AJOU [U4.66.01] and that of the forces
added by CALC_FORC_AJOU can be launched simultaneously using the macro-command
MACRO_MATR_AJOU [U4.66.11].

Product a concept of the vect_asse_gene_R type
Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Operator CALC_FORC_AJOU


Date:
19/01/05
Author (S):
NR. GREFFET, G. DEVESA, D. NUNEZ Key
:
U4.66.03-B Page
: 2/6

2 Syntax

forceaj
[vect_asse_gene_R] = CALC_FORC_AJOU


(
MODELE_FLUIDE
=
fluid
[model]




MODELE_INTERFACE
=
interf
[model]




CHAM_MATER
=
matflui [cham_mater]




CHARGE
=
charge
[char_ther]




/
MODE_MECA
=
modes
[mode_meca]
/
MODELE_GENE
=
modgen
[modele_gene]





NUME_DDL_GENE=
numgen
[nume_ddl_gene]



DIST_REFE
=
/
outdistance
[R]
/
1.E-2
[DEFAUT]



AVEC_MODE_STAT
=
/
“OUI”
[DEFAUT]










/“NON”



DIRECTION
= to dir
[l_R]



/MONO_APPUI
=
“OUI”
/
MODE_STAT
=

mode [mode_stat_depl]






/
NOEUD
=
No [l_noeud]
/
GROUP_NO
=
grno
[l_gr_noeud]



NUME_MODE_MECA
=
nume [l_I]



INFO
=
/
1
[DEFAUT]







/2



POTENTIEL
=
phi
[evol_ther]



SOLVEUR
=
to see
[U4.50.01]



NOEUD_DOUBLE
=/“OUI”
/
“NON”
[DEFAUT]


);
Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Operator CALC_FORC_AJOU


Date:
19/01/05
Author (S):
NR. GREFFET, G. DEVESA, D. NUNEZ Key
:
U4.66.03-B Page
: 3/6

3 Operands

3.1 Operand
MODELE_FLUIDE

MODELE_FLUIDE = fluid

Thermal model which one assigns to the part of the grid which corresponds to the fluid. Elements of
edge with the fluid interface/structure must be present in the fluid model. It is on this model
that one solves the equation of Laplace with boundary condition of the type “flow fluid”, to have it
field of pressure in all the fluid and a fortiori the field of pressure to the interface
fluid/structure.

The nodes of the elements of the fluid grid must all be numbered so that it
jacobien of the element is of positive sign on all the fluid grid.

3.2 Operand
MODELE_INTERFACE

MODELE_INTERFACE = interf

Thermal model of interface gathering all the elements of edge defining the interface
fluid/structure. It is on this model that one calculates the terms of the added matrices.

Calculation depends on the orientation of the normal of these elements of interface. It is necessary to take care of it
that this normal is directed towards all these elements, from the structure towards the fluid (convention
adopted).

If the fluids bathing the structure are different densities, the model should be defined interfaces
by as many groups of meshs not confused geometrically than there are fluids with the contact
structure. For example, a piping can have its interior surface in contact with a fluid
of density 1, and its surface external in contact with a fluid of density 2. The model interface is
thus built on two groups of meshs not confused geometrically, one in contact with
fluid of density 1 (interfa1) and the other in contact with the fluid of density 2 (interfa2).

interfa2
I
NR
interfa1
T
fluid 1
E
R
F
With
C
E
fluid 2
structure

Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Operator CALC_FORC_AJOU


Date:
19/01/05
Author (S):
NR. GREFFET, G. DEVESA, D. NUNEZ Key
:
U4.66.03-B Page
: 4/6

3.3 Operands
CHAM_MATER/LOAD

CHAM_MATER = matflui

Material field defining the fluid immersing the structure. This material is defined by
equivalent thermal characteristics in operator DEFI_MATERIAU [U4.43.01].
thermal conductivity (key word LAMBDA) is always taken equalizes to 1. Specific heat
(key word RHO_CP) the role of density of the fluid plays.

CHARGE = load

Thermal load of type [char_ther] necessary to the resolution of the linear system rising
equation of Laplace in the fluid. One must impose an unspecified temperature (which plays in
fact the role of a pressure) on an unspecified node of the fluid grid, in order to return the system
not singular. This operation is carried out with operator AFFE_CHAR_THER [U4.44.02].

3.4 Operands
MODE_MECA/MODELE_GENE

/MODE_MECA = modes

Dynamic modes calculated on the model structure. If there are several structures not
related immersed in the same fluid, for which one wants to determine the matrices
added including/understanding the terms of coupling by the fluid, the model structure which one defines
gather the totality of the immersed structures. The modes used by the operator are them
modes calculated for the total structure.


/MODELE_GENE = modgen

Generalized model built by operator DEFI_MODELE_GENE [U4.65.02]. This key word is with
to use when one makes a calculation by dynamic under-structuring, and that one wants to calculate
stamp of added mass coupling the whole of the substructures. In this case, under
structures can be in different files of grid, these files being able to be them
same distinct from the fluid file of grid. The substructures which present one
repetitivity within the fluid are to be netted only only once, but one will take care with
level of the fluid grid to net all the interfaces fluid/structure. Moreover, it is necessary to take care
so that the nodes of fluid interface coincide as well as possible with the nodes of interface of
structure, in order to be able to recopy, on the basis of geometrical criterion of proximity, them
values of the fields of displacement of structure on the nodes of fluid interface (see
operand DIST_REFE).

3.5 Operand
DIST_REFE

Outdistance reference to be informed when one makes a calculation of force added on a generalized model.
This distance is a geometrical absolute criterion intended to recopy values of displacements
structural in a thermal fluid model, in order to solve there the equation of Laplace of the field of
non stationary pressure. By defect, it is equal to 10­2 Mr.

Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-66/05/004/A

Code_Aster ®
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Titrate:
Operator CALC_FORC_AJOU


Date:
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Author (S):
NR. GREFFET, G. DEVESA, D. NUNEZ Key
:
U4.66.03-B Page
: 5/6

3.6 Operand
NOEUD_DOUBLE


NOEUD_DOUBLE = “YES”

This operand is to be used when one makes a calculation of force added starting from a model
generalized which includes/understands a substructure with a grid by a telegraphic or surface grid (i.e without
thickness like beam or hull) and surrounded by two fluids. It is necessary in this case for the level of
grid to duplicate the nodes of the fluid interfaces of those of the structure, in order to be able
to calculate the hydrodynamic jump of pressure on both sides of the structure (cf appears
below).

X X X
X X
X
X
X
X
X
X
Structure with a grid
fluid 1
X
X
(without thickness)
X
X
X
X
X
X
Duplicated nodes
X
X
X
X
X X
(nodes having the same ones
co-ordinates but not it
fluid 2
even name)


3.7 Operand
POTENTIEL


POTENTIEL = phi

Potential (thermal) stationary necessary to the calculation of damping and rigidity added
structure subjected to a potential flow. This potential is produced by the operator
THER_LINEAIRE [U4.54.01].

3.8 Operand
DIRECTION

DIRECTION = (d1, d2, d3, r1, r2, r3)

Components of a vector giving the direction of the seism of drive in the total reference mark.
It is a list of three realities if the imposed accélérogrammes are only translations. If
one also imposes accelerations of rotations, one awaits a list of six realities (valid for
modelings with discrete elements).

3.9
Description of the movement of drive

3.9.1 Operand
MONO_APPUI

/MONO_APPUI = “YES”

The structure is uniformly excited in all the supports (movement of drive of body
solid).
Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Operator CALC_FORC_AJOU


Date:
19/01/05
Author (S):
NR. GREFFET, G. DEVESA, D. NUNEZ Key
:
U4.66.03-B Page
: 6/6

3.9.2 Excitation multi supports

In this case, the accelerations undergone by the whole of the points of anchoring of the studied structure
are not inevitably identical and in phase.

3.9.2.1 Operand
MODE_STAT


/
MODE_STAT = mode

Static modes of the structure: concept of the mode_stat_depl type produced by
operator MODE_STATIQUE [U4.52.14] with option DDL_IMPO. They correspond to the 3
or 6 * nb_supports static modes where nb_supports is the number of accélérogrammes
different undergone by the structure.

Note:

If the structure is requested only by translations, there are then 3 nb_supports
static modes.

3.9.2.2 Operands
NODE/GROUP_NO

/NOEUD = No

/
GROUP_NO = grno

List nodes (No) or groups of nodes (grno) of the structure subjected to the excitation
seismic: these nodes support the ddl supports of the structure to which are
applied imposed movements.

3.10 Operand
NUME_DDL_GENE

NUME_DDL_GENE = numgen

Generalized classification based on the mechanical modes of the total structure.
presence of this operand makes it possible to calculate a matrix of added mass of type
matr_asse_gene_R. It must be necessarily present if one wants to make thereafter
modal, harmonic or transitory calculation.
3.11 Key word factor SOLVEUR

See [U4.50.01].

3.12 Operand
AVEC_MODE_STAT

Allows to disconnect the calculation of the terms of mass added on the static modes contained in
the modal base of the substructures in the case of a calculation with a generalized model (cf [§3.4]).

3.13 Operand
NUME_MODE_MECA

Allows to specify a list of numbers of modes retained for calculation.

3.14 Operand
INFO

INFO
=

Indicate the level of impression of the results of the operator on file MESSAGE.

1: no impression
2: impression of the terms of added force.
Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-66/05/004/A

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