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Modal analysis with LIAISON_MAILAGE [CODE_ASTER]

  • Martin Creek
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10 years 5 months ago #7744 by Martin Creek
Hello Everyone,

im having a problem trying to perform a modal analysis of an assembly. The general idea is that the assembly consists of a plate (PCB) and an element soldered to it - both different materials. I've tried different tutorials concerning using LIAISON_MAIL. They propose different approaches to modeling simmilar cases (begining from meshing) but the closest i think i got to a solution is:

Meshing a single compund solid consisting of both my general solids and mesh groups. Then my code looks like this:

DEBUT();

MAIL=LIRE_MAILLAGE(UNITE=20,
FORMAT='MED',
VERI_MAIL=_F(VERIF='OUI',),);

MODELE=AFFE_MODELE(MAILLAGE=MAIL,
AFFE=_F(TOUT='OUI',
PHENOMENE='MECANIQUE',
MODELISATION='3D',),);

FR4=DEFI_MATERIAU(ELAS=_F(E=2.4e5,
NU=0.135,
RHO=2.5e-9,),);

STAL=DEFI_MATERIAU(ELAS=_F(E=21000000,
NU=0.3,
RHO=7.9e-08,),);

CHMAT=AFFE_MATERIAU(MAILLAGE=MAIL,
AFFE=(_F(GROUP_MA='Fuse_1',
MATER=STAL,),
_F(GROUP_MA='Cut_1',
MATER=FR4,),),);

BLOCAGE=AFFE_CHAR_MECA(MODELE=MODELE,
DDL_IMPO=_F(GROUP_MA='Fix',
DX=0.0,
DY=0.0,
DZ=0.0,),
LIAISON_MAIL=_F(GROUP_MA_MAIT='OTW',
GROUP_MA_ESCL='BOLC',
TYPE_RACCORD='MASSIF',),);

MACRO_MATR_ASSE(MODELE=MODELE,
CHAM_MATER=CHMAT,
CHARGE=BLOCAGE,
NUME_DDL=CO('NUMEDDL'),
MATR_ASSE=(_F(MATRICE=CO('RIGIDITE'),
OPTION='RIGI_MECA',),
_F(MATRICE=CO('MASSE'),
OPTION='MASS_MECA',),),);

MODES=MODE_ITER_SIMULT(MATR_A=RIGIDITE,
MATR_B=MASSE,
CALC_FREQ=_F(OPTION='PLUS_PETITE',
NMAX_FREQ=5,),);

IMPR_RESU(MODELE=MODELE,
FORMAT='MED',
RESU=_F(MAILLAGE=MAIL,
RESULTAT=MODES,
NOM_CHAM='DEPL',),);

FIN();


[u]Unfortunately i get an error like this when attempting to solve the case:[/u]

BLOCAGE=AFFE_CHAR_MECA(INFO=1,
DDL_IMPO=_F(GROUP_MA='Fix',
DZ=0.0,
DX=0.0,
DY=0.0),
LIAISON_XFEM='NON',
LIAISON_MAIL=_F(GROUP_MA_ESCL='BOLC',
ELIM_MULT='NON',
TYPE_RACCORD='MASSIF',
GROUP_MA_MAIT='OTW'),
VERI_NORM='OUI',
MODELE=MODELE,
);


!
!
! <EXCEPTION> <CALCULEL4_55> !
! !
! pas de mailles a projeter. !
!
!


Destruction du concept 'BLOCAGE'.

!
!
! Liste des alarmes émises lors de l'exécution du calcul. !
! !
! Les alarmes que vous avez choisies d'ignorer sont précédées de (*). !
! Nombre d'occurrences pour chacune des alarmes : !
! aucune alarme !
!
!

What is my problem?

Kind Regards
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10 years 5 months ago #7750 by kwou
Hoi Martin

can you add your complete *.mess file, that is easier to read and gives more detail.
Maybe something is wrong in your ''contact'' definition ...(LIAISON_MAIL=_F(GROUP_MA_MAIT='OTW',GROUP_MA_ESCL='BOLC',TYPE_RACCORD='MASSIF',),);

BTW:
Are you sure your steel data (youngs' module and RHO) are correct?
Same remark for E of FR4?

Interest: structural mechanics, solar energy (picture at 'my location' shows too little pv panels)

--
kind regards - kees
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10 years 5 months ago #7751 by RichardS
Hello, it seems that you are using surface elements for the master group, but for 3d connections (MASSIF) you have to use volume elements for the master (GROUP_MA_MAIT).

Best regards,
Richard

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