Code_Aster ®
Version
7.4
Titrate:
Operator MODE_ITER_CYCL


Date:
08/03/05
Author (S):
O. NICOLAS, E. BOYERE Key
:
U4.52.05-G Page
: 1/6

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

Handbook of Utilization
U4.5- booklet: Methods of resolution
Document: U4.52.05

Operator MODE_ITER_CYCL

1 Goal

To calculate the clean modes of a structure with cyclic symmetry.

One calculates the generalized components of the clean modes of the whole structure, by a method
of cyclic under-structuring, starting from the modal base of a sector of reference. The axis of symmetry
is axis OZ. The modal base of the sector must be of type CLASSIQUE. Interfaces DROITE,
GAUCHE and possibly AXE must be in the same way standard. The sides right and left are defined by
the trigonometrical direction in plan OXY.

Product a structure of data of the mode_cycl type.
Handbook of Utilization
U4.5- booklet: Methods of resolution
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Operator MODE_ITER_CYCL


Date:
08/03/05
Author (S):
O. NICOLAS, E. BOYERE Key
:
U4.52.05-G Page
: 2/6

2 Syntax
mocy [mode_cycl] = MODE_ITER_CYCL


(
BASE_MODALE
=
bamo,
[base_modale]




NB_MODE =
/
nbmo,
[I]








/999
,
[DEFAUT]



NB_SECTEUR
=
nbsec,
[I]



LIAISON = _F (

DROITE
=
“nom_int”,
[KN]










GAUCHE
=
“nom_int”,
[KN]









AXE
=
“nom_int”, [kN]








),



CALCUL = _F (
TOUT_DIAM
=/“OUI”,









NB_DIAM = Li, [l_I]










OPTION =/“PLUS_PETITE”,
[DEFAUT]
/
“CENTER”,
/
“BANDE”,










FREQ = lifreq,


[l_R]










NMAX_FREQ =/nbfreq,

[I]










/
10,
[DEFAUT]










PREC_SEPARE =
/
pre_sep,
[R]










/
1.E+2,
[DEFAUT]










PREC_AJUSTE =
/
pre_ajus,
[R]










/
1.E-6,
[DEFAUT]










NMAX_ITER
=
/
niter,
[I]










/
50,
[DEFAUT]








),




VERI_CYCL = _F (
PRECISION
=/prec, [R]
/
1.D-3,
[DEFAUT]











CRITERE =
/“RELATIVE”, [DEFECT]











DIST_REFE =
dist_ref, [R]









),




INFO =

/
1,
[DEFAUT]








/2,



)
Handbook of Utilization
U4.5- booklet: Methods of resolution
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Operator MODE_ITER_CYCL


Date:
08/03/05
Author (S):
O. NICOLAS, E. BOYERE Key
:
U4.52.05-G Page
: 3/6

3 Operands

3.1 Operand
BASE_MODALE

BASE_MODALE = bamo

Name of the modal base of the sector built by DEFI_BASE_MODALE [U4.64.02].

3.2 Operand
NB_MODE


NB_MODE = nbmo

A number of modes clean of the sector to be used for cyclic calculation. By defect, if the key word
does not appear, all the clean modes of the modal base are used.

3.3 Operand
NB_SECTEUR

NB_SECTEUR = nbsec

A number of basic sectors necessary to the construction of the total structure.

3.4 Word
key
LIAISON

LIAISON

Key word factor for the definition of the connections between the sectors.

3.4.1 Operands
LEFT STRAIGHT LINE//AXIS

See [Figure 3.6-a].


DROITE = “nom_int”

Name of the right interface of the sector.


GAUCHE = “nom_int”

Name of the left interface of the sector.



AXE = “nom_int”

Name of the interface of the axis of the sector.
They are points common to all the sectors.

3.5 Word
key
CALCUL

CALCUL

Key word factor to define it mode of search of the clean modes.

3.5.1 Operands
TOUT_DIAM/NB_DIAM



TOUT_DIAM = “YES”

The modes associated with all the numbers of nodal diameters will be calculated.



NB_DIAM = Li

List numbers of nodal diameters to calculate. By defect, all the numbers of
possible nodal diameters are studied.
Handbook of Utilization
U4.5- booklet: Methods of resolution
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Operator MODE_ITER_CYCL


Date:
08/03/05
Author (S):
O. NICOLAS, E. BOYERE Key
:
U4.52.05-G Page
: 4/6

3.5.2 Operand
OPTION



OPTION =

“PLUS_PETITE”
: to calculate by a method of iteration reverses the clean modes
corresponding to the smallest frequencies for each number of
diameters requested.
“CENTER”:
to calculate the clean modes centered around a frequency requested
by key word LIST_FREQ.
“BANDE”
:
to calculate the clean modes between two frequencies given by
the user by key word LIST_FREQ.
The Eigen frequencies are separated by dichotomy then the modes
clean calculated by iterations opposite centered on the frequencies
exits of the stage of separation.

3.5.3 Operands
FREQ/NMAX_FREQ



FREQ = lifreq

List frequencies of which the use depends on the selected option:

OPTION
=
“BANDE”


One awaits 2 values (F F
1
2) which defines the tape.

OPTION
=
“CENTER”


1 is awaited value which is the center frequency of the interval.

OPTION
=
“PLUS_PETITE”


One calculates the smallest Eigen frequencies of the structure. By defect, one calculates them
10 first. Key word FREQ then does not have a direction in this case, it does not have to be
informed.



NMAX_FREQ = nbfreq

A number of frequencies to be calculated for each number of nodal diameters asked. If it
key word does not appear, one calculates as many frequencies, for each nodal diameter, that there is
clean modes used in the modal base (key word NB_MODE).

3.5.4 Operands
PREC_SEPARE/PREC_AJUSTE/NMAX_ITER



PREC_SEPARE = pre_sep

Precision of separation of the frequencies for option “BANDE”.



PREC_AJUSTE = pre_ajus

Precision used for the calculation of modes (all OPTIONS).



NMAX_ITER = niter

Numbers maximum iterations opposite (all OPTIONS).
Handbook of Utilization
U4.5- booklet: Methods of resolution
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Operator MODE_ITER_CYCL


Date:
08/03/05
Author (S):
O. NICOLAS, E. BOYERE Key
:
U4.52.05-G Page
: 5/6

3.6 Word
key
VERI_CYCL

VERI_CYCL

Key word for checking of the coherence of the interfaces given in cyclic term of repetitivity.

Interface left
Y
Interface axis
Z
X
Interface right

Appear 3.6-a

3.6.1 Operands
PRECISION/DIST_REFE


PRECISION = prec

DIST_REFE = dist_ref

The test of coherence between 2 contiguous sectors will be determined by the product prec * dist_réf. If
DIST_REFE is not indicated, it will be automatically calculated proportionally with prec and with
a maximum value of co-ordinate of a sector.

3.7 Operand
INFO


INFO =

Level of impression

1
no impression,
2
writing of the frequencies and generalized parameters obtained and the participations
relative of the various modes of the base.

Handbook of Utilization
U4.5- booklet: Methods of resolution
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Operator MODE_ITER_CYCL


Date:
08/03/05
Author (S):
O. NICOLAS, E. BOYERE Key
:
U4.52.05-G Page
: 6/6

4
Cyclic under-structuring example

ANNULAR PLATE ENCASTREE ON A HUB - METHOD OF CRAIG-BAMPTON

sector = LIRE_MAILLAGE
(
)
model = AFFE_MODELE

(
MAILLAGE=
sector,
AFFE

=_F (ALL = ' OUI',







PHENOMENON = ' MECANIQUE',






MODELISATION=' DKT')
)
to subdue = DEFI_MATERIAU
(ELAS =_F (E=2.E11, NU=0.3, RHO=7800.0)
)
chammat = AFFE_MATERIAU
(MAILLAGE= sector,
AFFE =_F (TOUT = ' OUI', MATER= MATER)
)
chamcar = AFFE_CARA_ELEM
(MODELE = model,
HULL = (ALL = ' OUI', EPAIS= 0.001)
)
charge = AFFE_CHAR_MECA
(MODELE = model
DDL_IMPO= (TOUT=' OUI', DX=0., DY=0., DRZ=0.),



DDL_IMPO= (GROUP_NO=' AXE', DZ=0., DRX=0., DRY=0.),




DDL_IMPO= (GROUP_NO=' DROIT', DZ=0., DRX=0., DRY=0.),

DDL_IMPO= (GROUP_NO=' GAUCH', DZ=0., DRX=0., DRY=0.))
#
#
CONSTRUCTION OF THE MATRICES OF RIGIDITY AND MASS OF THE BASIC SECTOR
#
rigiele = CALC_MATR_ELEM (MODELE = model, CHARGE = load,

CHAM_MATER= chammat, CARA_ELEM = chamcar,
OPTION = “RIGI_MECA”
)
massele = CALC_MATR_ELEM (MODELE = model,
CHARGE = load,
CHAM_MATER= chammat, CARA_ELEM = chamcar,
OPTION = ' MASS_MECA')
numerot = NUME_DDL

(MATR_RIGI
=
rigiele)
matrigi = ASSE_MATRICE

(MATR_ELEM = rigiele, NUME_DDL = numerot
)
matmass = ASSE_MATRICE

(MATR_ELEM = massele, NUME_DDL = numerot
)
#
#



CALCULATION OF THE DYNAMIC MODES OF THE BASIC SECTOR
#
modes = MODE_ITER_SIMULT
(MATR_A = matrigi, MATR_B = matmass,

CALC_FREQ= _F (NMAX_FREQ= 15)



)
#
#
DEFINITION OF THE INTERFACES AND THE STATIC MODES ASSOCIATE
#
lint = DEFI_INTERF_DYNA
(NUME_DDL = numerot, IMPR= 2,
INTERFACE= _F (NOM=' DROITE', TYPE=' CRAIGB',
GROUP_NO=
“DROIT”,





MASQUE= (“DX”, “DY”, “DRZ”),),

INTERFACE= _F (NOM=' GAUCHE', TYPE=' CRAIGB',
GROUP_NO=
“GAUCH”,

MASQUE= (“DX”, “DY”, “DRZ”)))
#
#
CALCULATION OF THE BASE OF PROJECTION = RECOVERY OF THE DYNAMIC MODES
# AND CALCULATION OF THE STATIC MODES
bamo = DEFI_BASE_MODALE
(CLASSIQUE= _F (INTERF_DYNA= lint, IMPR= 2,



MODE_MECA = modes,
NMAX_MODE=
15
)

)
#
#

CALCUL
DES
MODES
CYCLIQUES
#
modcyc = MODE_ITER_CYCL (BASE_MODALE= bamo, NB_MODE=15, NB_SECTEUR=18,
LIAISON=_F (“RIGHT” DROITE=,
“LEFT” GAUCHE=),
CALCULATION =_F (NB_DIAM= (0, 1, 2, 3), NMAX_FREQ=2))

Handbook of Utilization
U4.5- booklet: Methods of resolution
HT-66/05/004/A

Outline document