DYNA_LINE_TRAN /DYNA_TRAN_MODAL help

hi Kees
Thanks for all your help it ha been great and also for all the contributions to the wiki.

i am just running into a bit of a problem when i use the DIFF_CENTRE. i get an error about the intervals(pas)

trans=DYNA_LINE_TRAN(MODELE=MODELE,
CHAM_MATER=CHMAT,
MATR_MASS=MASSE,
MATR_RIGI=RIGIDITE,
MATR_AMOR=C,
DIFF_CENTRE=_F(),
EXCIT=_F(CHARGE=FORCE,
FONC_MULT=PRESS,),
INCREMENT=_F(PAS=0.00625,
INST_INIT=0,
INST_FIN=5,),);

it would be great if you could have a look at it.
thanks
Kyle

P.S here is what I am using for the newmark method that I said I would post
# PATRON
# ANALYSE MODALE
# 3D

DEBUT();

# MISE EN DONNEES

MAIL=LIRE_MAILLAGE(UNITE=20,
FORMAT='MED',
INFO=1,);

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

# MATERIAU

ACIER=DEFI_MATERIAU(ELAS=_F(E=207000000000.0,
NU=0.292,
RHO=7850.0,
AMOR_ALPHA=0.8e-4,
AMOR_BETA=0.0,),);

CHMAT=AFFE_MATERIAU(MAILLAGE=MAIL,
AFFE=_F(TOUT='OUI',
MATER=ACIER,),);

# CONDITIONS AUX LIMITES ET CHARGEMENT
# CONDITIONS AUX LIMITES

test=DEFI_LIST_REEL(DEBUT=0.0,
INTERVALLE=_F(JUSQU_A=5.0,
PAS=0.00625,),);

BLOQUAGE=AFFE_CHAR_MECA(MODELE=MODELE,
DDL_IMPO=_F(GROUP_MA='fix',
DX=0.0,
DY=0.0,
DZ=0.0,),);

# CALCUL DES MATRICES ASSEMBLEES K ET M

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

FORCE=AFFE_CHAR_MECA(MODELE=MODELE,
PRES_REP=_F(GROUP_MA='force',
PRES=35000.0,),);
#this is used to apply the force/pressure for 0.05s then nothing
# after that

def APPLYFORCE(x) :
if x == 0.05 : return 1
return 0

PRESS = FORMULE(VALE='APPLYFORCE(INST)',
NOM_PARA='INST',);

#CALCUL TRANSITOIRE

trans=DYNA_LINE_TRAN(MODELE=MODELE,
CHAM_MATER=CHMAT,
MATR_MASS=MASSE,
MATR_RIGI=RIGIDITE,
MATR_AMOR=C,
NEWMARK=_F(ALPHA=0.25,
DELTA=0.5,),
EXCIT=_F(CHARGE=FORCE,
FONC_MULT=PRESS,),
INCREMENT=_F(LIST_INST=test,),);

#IMPR_RESU(MODELE=MODELE,
# FORMAT='MED',
# UNITE=21,
# RESU=_F(MAILLAGE=MAIL,
# RESULTAT=trans,),
# INFO=1,);

TB_nodf=POST_RELEVE_T(ACTION=_F(OPERATION='EXTRACTION',
INTITULE='velocity',
RESULTAT=trans,
NOM_CHAM='VITE',
TOUT_ORDRE='OUI',
NOEUD='N5076',
RESULTANTE='DZ',
MOYE_NOEUD='NON',),
TITRE='Velocity top of plate',);

IMPR_TABLE(TABLE=TB_nodf,
FORMAT='TABLEAU',
UNITE=26,
SEPARATEUR=' * ',
TITRE='Velocity at node',);

FIN();

hi
i am using quad hex and quad tetra elements, i really need the DiFF_CENTRE to work so i can compare my results to the newmark method.
I get the following error message
! <EXCEPTION> <DYNAMIQUE_12> !
! !
! !
! Le pas de temps est trop grand : 0.006250 !
! le pas de temps maximal est : 0.000000 !
! !
! Avec le pas de temps maximal, le nombre de pas de calcul est 259693160 !
! !
! !
! !
! !
!

---

!
I also know that i can only use diagonal mass matrix for the adaptive and difference methods.

I will say how i got the damping a bit later. i have written it twice now and every time it losses it when i try to post it.
Thanks
Kyle<br /><br />Post edited by: Kyle Moon, at: 2009/10/14 15:06