Welcome to the forums. Please post in English or French.

You are not logged in.

#1 2022-07-29 15:19:18

Matt141
Member
Registered: 2022-04-07
Posts: 22

How to troncate a modal base ?

Hi everyone,

I use DYNA_VIBRA to calculate vibration field on a structure as a response to a nodal force. I'd like to calculate this vibration field for only one mode of a modal base.

So, I selected one mode with EXTR_MODE:

MODE1 = EXTR_MODE ( FILTRE_MODE = _F ( MODE = MODES,
                                       NUME_MODE = (20)),)  

And then I try to project the masse matrix and rigidity matrix to this new mode:

MGENE1=PROJ_MATR_BASE(BASE=MODE1,
                     NUME_DDL_GENE=NUMGEN,
                     MATR_ASSE=M_ASSE,);

in order to be used in DYNA_VIBRA, as below.

## Calcul dynamique par la methode modale ##
	DYNGENE=DYNA_VIBRA(BASE_CALCUL='GENE',
		           TYPE_CALCUL='HARM',
		           MATR_MASS=MGENE1, 
		           MATR_RIGI=KCGENE1, 
		           LIST_FREQ=FREQ,
		           EXCIT=_F(VECT_ASSE_GENE=FGENE,
		                    COEF_MULT=1,),
		           AMOR_MODAL = _F(AMOR_REDUIT=AMOR_REDUIT),  
		           );

But I get the following error on PROJ_MATR_BASE

║ <EXCEPTION> <DVP_1>                                                                            ║
║                                                                                                ║
║ Erreur de programmation.                                                                       ║
║                                                                                                ║
║ Condition non respectée:                                                                       ║
║     nbmodes .le. nbmode

It seems that changing the number of modes is an issue.  Do you know why? You can find the mess file attached to this message.
Regards,
Mathieu


Attachments:
mess_structure_poursuite_mode.txt, Size: 49.96 KiB, Downloads: 54

Offline