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#1 2021-10-08 11:05:12

JanBlokes
Member
From: Koprivnice
Registered: 2018-09-06
Posts: 15

Dynamic analysis with multi-support

Hello everybody,

I wonder about dynamic analysis with multi-support where I want to put excitation (displacement or acceleration dependent on time). First I tried a solution with one support where I put excitation (acceleration in X,Y and Z directions). I used CALC_CHAR_SEISME (with MONO_APPUI = 'OUI') and DYNA_VIBRA. It works well.

Please see the attachment with some pictures which describes the problem.

Regarding multi-supports I have found a testcase SDLD103 with MODE_STATIQUE, multiple CALC_CHAR_SEISME and DYNA_VIBRA (MULT_APPUI = 'OUI') so far. I don't understand why I have to input all three DEPL, VITE and ACCE in EXCIT. Is it because of possibility with different phases? I'm able to get the displacement and velocity from acceleration signal or vice versa but just wondering why is it necessary.

Or would anybody recommend other option with multi-supports in DYNA_VIBRA?

Thank you for any idea.
Jan


Attachments:
Description.pdf, Size: 217.52 KiB, Downloads: 27

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#2 2021-10-09 13:39:48

jeanpierreaubry
Guru
From: nantes (france)
Registered: 2009-03-12
Posts: 3,648

Re: Dynamic analysis with multi-support

hello

MUMT_APPUI = 'NON', means that all the ground connection (there  may any number of them) are submitted to the same load, DEPL, VITE and ACCE in EXCIT.
with MULT_APPUI = 'OUI'  each ground connection is submitted to a different load, DEPL, VITE and ACCE in EXCIT.

jean pierre aubry


consider reading my book
freely available here https://framabook.org/beginning-with-code_aster/

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#3 2021-10-11 10:22:01

JanBlokes
Member
From: Koprivnice
Registered: 2018-09-06
Posts: 15

Re: Dynamic analysis with multi-support

jeanpierreaubry wrote:

hello

MUMT_APPUI = 'NON', means that all the ground connection (there  may any number of them) are submitted to the same load, DEPL, VITE and ACCE in EXCIT.
with MULT_APPUI = 'OUI'  each ground connection is submitted to a different load, DEPL, VITE and ACCE in EXCIT.

jean pierre aubry


Hello Jean Pierre,

thank you for the reply. Don't you know why is there necessary to input all DEPL, VITE and ACCE? Is the software unable to  differentiate and integrate or is there any other reason? I always thought that in one point is valid only one BC. In this case I mean either DEPL or VITE or ACCE. Sorry for maybe stupid question.

Jan

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#4 2021-10-12 08:14:15

sameer21101970
Member
Registered: 2019-09-06
Posts: 353

Re: Dynamic analysis with multi-support

Hello Jean Pierre,

Your Book is like Bible to Code Aster.

One Request to you, There are so Many Commands in CodeAster, Commands Definition lot of confusion. Can you bring more clarity by publishing book or pdf  in forum. for example your explanation above on [ DYNA_VIBRA (MULT_APPUI = 'OUI') ].

Thanks for your unrelenting help.

Regards
Sameer Shah

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#5 2021-10-12 09:26:50

jeanpierreaubry
Guru
From: nantes (france)
Registered: 2009-03-12
Posts: 3,648

Re: Dynamic analysis with multi-support

hello

thanks for the kind comments about my book

i have a second one dealing with dynamics almost finished but the publisher (Framabook) has somehow decided to stop, i am looking for a solution !

now about our problem
lets suppose we have a table with 4 legs connection to the ground named 'fixne','fixnw','fixse','fixsw',

the following does a seismic calculation with 2 sets of fixation  submitted to an acceleration seismic load
(in this example the load spectrum is actually the same on all connection but it could be adapted to a different 'aceartq')

here we use only acceleration as a load

before the actual code one remark in normal construction work a different spectrum on some connection to the ground seems very rare to me

one example could be a bridge connecting the top of two buildings
for each of these buildings one has performed  a seismic analysis retrieving a different spectrum at the top
which the applied at the 2 ends of the bridge

#acceleration spectrum by eurocode

#T* are instant in seconds
TB=0.1;
TC=0.4; 
TC18=0.73; 
TC14=1.05; 
TC24=1.7;
TC34=2.35;
TD=3.0;
TD2=6.0;
#a* are acceleration at the same instant in m/s^2
a0=1.1;
aB=5.08;
aC=5.08;
aC18=2.8;
aC14=1.94;
aC24=1.2;
aC34=0.86;
aD=0.68;
aD2=0.17;

aceartq=DEFI_FONCTION(
	NOM_PARA='INST',
	VALE=(
		0,a0, 
		TB,aB, 
		TC,aC, 
		TC18,aC18, 
		TC14,aC14, 
		TC24,aC24, 
		TC34,aC34, 
		TD,aD, 
		TD2,aD2
	),
	PROL_GAUCHE='EXCLU',PROL_DROITE='CONSTANT',
);
#view an XmGrace plot of it, on the screen, on the fly
IMPR_FONCTION(
	FORMAT='XMGRACE',
	#PILOTE='INTERACTIF',
	UNITE=33,
	COURBE=(
		_F(
			FONCTION=aceartq,
			#LEGENDE='seism acceleration sepctrum',
			COULEUR=8,
		),
	),
	TITRE='Acceleration spectrum',
	LEGENDE_X='Time',
	LEGENDE_Y='g',
	BORNE_X=(0.0, 6),
	BORNE_Y=(-0.1, 5.5),
	GRILLE_X=1,
	GRILLE_Y=1.0,
);

accelfc=CALC_FONCTION(
	COMB=_F(FONCTION=aceartq,COEF=1.0,),
	PROL_DROITE='CONSTANT',
);

#list for calculation
listacc=DEFI_LIST_REEL(
	DEBUT=0.0,
	INTERVALLE=(
		_F(JUSQU_A=2*TD2,PAS=5e-4,),	
	),
);

#list for result
listresu=DEFI_LIST_REEL(
	DEBUT=0.0,
	INTERVALLE=_F(JUSQU_A=2*TD2,PAS=0.1,),
);

#U4.63.01 and R4.05.01
#this bit to be used with MONO_APPUI
dirseism=CALC_CHAR_SEISME(
	MATR_MASS=masse,
	DIRECTION=(1.0, 1.0, 0.1),
	MONO_APPUI='OUI',
);

modst=MODE_STATIQUE ( 
	MATR_RIGI=rigidity,
    MATR_MASS=masse,
    MODE_STAT=_F(
    	GROUP_NO=('fixne','fixnw','fixse','fixsw',),
    	AVEC_CMP=('DX','DY','DZ',),
    ), 
) ;

dirseis1=CALC_CHAR_SEISME(
	MATR_MASS=masse,
	DIRECTION=(1.0, 1.0, 0.1),
	#MONO_APPUI='OUI',
	MODE_STAT=modst,
	GROUP_NO='fixne',
);	

dirseis2=CALC_CHAR_SEISME(
	MATR_MASS=masse,
	DIRECTION=(1.0, 1.0, 0.1),
	#MONO_APPUI='OUI',
	MODE_STAT=modst,
	GROUP_NO=('fixnw','fixse','fixsw',),
);	

nbvect=10,

#project the assembled vector 
#on the previously calculated modal base
#U4.63.11	
PROJ_BASE(
	BASE=modes,
	NB_VECT=nbvect,
	MATR_ASSE_GENE=(
		_F(MATRICE=CO('stifGen'),MATR_ASSE=rigidity,),
		_F(MATRICE=CO('massGen'),MATR_ASSE=masse,),
	),
	VECT_ASSE_GENE=(
		_F(VECTEUR=CO('forcGen1'),VECT_ASSE=dirseis1,),
		_F(VECTEUR=CO('forcGen2'),VECT_ASSE=dirseis2,),
	),
);	

#xi=0.01;
listxi=DEFI_LIST_REEL(VALE=(0.01, 0.005, 0.005, 0.005,),);

#U4.72.01
amorG=COMB_MATR_ASSE(
	CALC_AMOR_GENE=_F(
		RIGI_GENE=stifGen,
		MASS_GENE=massGen,
		#AMOR_REDUIT=xi,
		LIST_AMOR=listxi,
	),
);	

seismG=DYNA_VIBRA(
	BASE_CALCUL='GENE',
	TYPE_CALCUL='TRAN',
	MATR_MASS=massGen,
	MATR_RIGI=stifGen,
	MATR_AMOR=amorG,	
	INCREMENT=_F(LIST_INST=listacc,),
	EXCIT=(
		_F(VECT_ASSE_GENE=forcGen1,FONC_MULT=accelfc,),
		_F(VECT_ASSE_GENE=forcGen2,FONC_MULT=accelfc,),
	),
);

and in case of a single APPUI


PROJ_BASE(
	BASE=modes,
	NB_VECT=nbvect,
	MATR_ASSE_GENE=(
		_F(MATRICE=CO('stifGen'),MATR_ASSE=rigidity,),
		_F(MATRICE=CO('massGen'),MATR_ASSE=masse,),
	),
	VECT_ASSE_GENE=(
		_F(VECTEUR=CO('forcGen'),VECT_ASSE=dirseism,),
	),
);
seismG=DYNA_VIBRA(
	BASE_CALCUL='GENE',
	TYPE_CALCUL='TRAN',
	MATR_MASS=massGen,
	MATR_RIGI=stifGen,
	MATR_AMOR=amorG,	
	INCREMENT=_F(LIST_INST=listacc,),
	EXCIT=(
		_F(VECT_ASSE_GENE=forcGen,FONC_MULT=accelfc,),
	),
);

if questions do not hesitate

jean pierre aubry

Last edited by jeanpierreaubry (2021-10-12 09:29:39)


consider reading my book
freely available here https://framabook.org/beginning-with-code_aster/

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#6 2021-10-13 10:18:45

JanBlokes
Member
From: Koprivnice
Registered: 2018-09-06
Posts: 15

Re: Dynamic analysis with multi-support

Thank you very much for the hint, Jean Pierre Aubry!

Your book is really inspiring and looking forward for the one regarding dynamic problems.

Jan

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