Code_Aster forums

Thanks for your reply Thomas,
I tried your method and It works, but because of my model and geometry, most of the
first buckling modes and frequencies are related to cables and it is logical.
To get the higher buckling loads in which the beam elements are affected, I increased the parameter NB_FREQ, and the
results have been better.
To view the buckling modes I am using the 'MODE_FLAMB parameter in IMPR_RESU, but it does not
show the defined number of frequencies in NB_FREQ.
for example I put the NB_FREQ=20 , and IMPR_RESU should show me 20 buckling modes in each time step of STAT_NON_LINE (in SALOME outpu) , but it only shows only 1 . How can I solve this problem ?



More over, I can only check  the critical loads from this line in mess file :

LES CHARGES CRITIQUES CALCULEES INF. ET SUP. SONT:
      CHARGE_CRITIQUE_INF :  3.81704E-02
      CHARGE_CRITIQUE_SUP :  2.11705E+00

which it seems that the first number is my first buckling load and the second number is the last buckling load, how can I have
all of 20 buckling loads defined in NB_FREQ in the output, or even better in SALOME med file?

Regards
FP

Dear Thomas , Thanks for your answers,

Keeping aside the buckling loads,
Is there any way to find the natural vibration frequencies (eigen values) and mode shapes of the mentioned cable structure?
my analysis is 'GDEP_GROT'  but the material behavior is elastic.
For example can I use the ' DYNA_NON_LINE' command or other one to do this, I only need the eigen values and mode shapes,
without applying any kind of dynamical load or even modal damping.
If it is possible, How can I output the mode shapes in med file?

All the best,
FP

Hi, Thomas

I used the DYNA_NON_LINE command with MODE_VIBR, but I got the following error :

Post-traitement: calcul d'un mode vibratoire

   
   !-----------------------------------------------------------------------------------------------------------!
   ! <EXCEPTION> <CALCULEL_30>                                                                                 !
   !                                                                                                           !
   ! Erreur utilisateur :                                                                                      !
   !   -> Le TYPE_ELEMENT MECABL2  ne sait pas encore calculer l'OPTION:  RIGI_MECA.                           !
   !                                                                                                           !
   !   -> Risques & Conseils :                                                                                 !
   !    * Si vous utilisez une commande de "calcul" (THER_LINEAIRE, STAT_NON_LINE, ...), il n'y a pas          !
   !      moyen de contourner ce probl�me.Il faut changer de mod�lisation ou  �mettre une demande d'�volution. !
   !                                                                                                           !
   !    * Si c'est un calcul de post-traitement, vous pouvez sans doute "�viter" le probl�me                   !
   !      en ne faisant le post-traitement que sur les mailles qui savent le faire.                            !
   !      Pour cela, il faut sans doute utiliser un mot cl� de type "GROUP_MA".                                !
   !      S'il n'y en a pas, il faut faire une demande d'�volution.                                            !
   !-----------------------------------------------------------------------------------------------------------!
   

Actually when I remove the MODE_VIBR from the command, it works, but I am only interested to natural frequencies at this step.
I do not want to apply any dynamical loads.

Thanks
FP

Ok , it worked. Is there a way to view the mode-shapes in med file ?
with IMPR_RESU , I used DEPL_VIBR, MODE_MECA, MODE_VIBRE but none of them worked.
I am using stable version (10.6).

Thanks
FP

Hi,

Sadly there's a bug in 10.6 and although the field is produced (MODE_MECA) I think it cannot be retrieved.

I'm afraid the simplest is to use a 11.1 version.

TdS