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

You are not logged in.

#1 Re: Salome-Meca usage » can i use xfem without define initial crack ? » 2021-06-18 13:38:43

no I worked on the modelization described in the document: V3.02.326. it is not a beam model.
The .hdf file is attached.

Thanks

#2 Re: Salome-Meca usage » can i use xfem without define initial crack ? » 2021-06-17 15:52:19

I took your advice and took a look at the SSLV315 document. but as I am a beginner on salome meca and that in SSLV315 there are not the steps to build the model I switched to the document forma01 where in the modelization D it is question of XFEM.
However, I have an error that I don't understand:

!----------------------------------------------------------------------------------------------------------------!
   ! <EXCEPTION> <CALCULEL_54>                                                                                      !
   !                                                                                                                !
   !  Le paramètre:  PSTANO  de l'option:  INI_XFEM_ELNO  n'est pas connu des TYPE_ELEM du LIGREL:  modlxfem.MODELE !
   !  Champ : modlxfem.STNO                                                                                         !
   !----------------------------------------------------------------------------------------------------------------!

Can you help me ?

the model is attached .

#3 Re: Salome-Meca usage » can i use xfem without define initial crack ? » 2021-06-14 15:36:02

thanks for your answer.
If it possible, so what do i have to do in the step "DEFI_FISS":

"FISS=DEFI_FISS_XFEM(MAILLAGE=MAILLA,
                                          TYPE_DISCONTINUITE = / 'FISSURE', [DEFAULT]
                                                                                    / 'INTERFACE'
                                          DEFI_FISS=_F()
                                          )
"

#4 Salome-Meca usage » can i use xfem without define initial crack ? » 2021-06-11 15:08:11

kadred
Replies: 6

Hello,

Is it possible to use XFEM without defining initial crack ?

In my model i dont have an initial crack, i would like to use xfem to predicts the crack initiation sites considering the applied boundary conditions. Is it possible ?

Thank you in advance for any help.

#5 Salome-Meca usage » variable young modulus following a direction of the geometrical space » 2020-08-08 14:23:40

kadred
Replies: 1

Hello,

I wish to have some details concerning the way of process to have a variable young modulus following a direction of the geometrical space.
At the end of Doc. U4.43.03 (Exemple 5 : Calcul mécanique avec un champ de module d'Young imposé) one gives an example on how to proceeds. on code-aster.org/forum2/viewtopic.php?id=17518 the subject was discussed there!

The procedure is as follows :

# 1-Create the field of the geometrical coordinates
CHAM_GEO=CREA_CHAMP(TYPE_CHAM='NOEU_GEOM_R',   
                OPERATION='EXTR',
                MAILLAGE=MAIL,
                NOM_CHAM='GEOMETRIE',);

# 2-Create a function of youngs modulus depending on Y-coordinate
YOUNG_Y = FORMULE(VALE='3.0E6*Y',               
                 NOM_PARA='Y',);

# 3-Create a field of functions (YOUNG_Y) per node
CH_FONC=CREA_CHAMP(TYPE_CHAM='NOEU_NEUT_F',     
                   OPERATION='AFFE',
                   MAILLAGE=MAIL,
                   AFFE=_F(
                   TOUT='OUI',
                   NOM_CMP='X1',
                   VALE_F=YOUNG_Y,),);

# 4-Evaluate the field CH_FONC with parameter field CHAM_GEO at each node
CHYOUNG=CREA_CHAMP(TYPE_CHAM='NOEU_NEUT_R',     
                   OPERATION='EVAL',
                   CHAM_F=CH_FONC,
                   CHAM_PARA=CHAM_GEO,);

After these four steps we have a field representing the young modulus on each node !!!

In U4.43.03 it's said :

"L' « astuce » consiste à définir un matériau pour lequel le module d'Young (mot clé ELAS/E) est la fonction "identité" de la variable 'NEUT1' et on affecte le champ CHYOUNG comme variable de commande 'NEUT1'."

# 5- define poisson coefficient "NU_F"
NU_F=DEFI_CONSTANTE (VALE=0.3);

# 6-define Young modulus "E_F"
E_F = DEFI_FONCTION (NOM_PARA='NEUT1',
                     VALE= (-1.E-9, -1.E-9,
                            1.E+9, 1.E+9));

# 7-define a material "MA"
MA=DEFI_MATERIAU (ELAS_FO=_F (E=E_F, NU=NU_F,),);

# 8- assign material "MA"
CM=AFFE_MATERIAU (MAILLAGE=M,
                  AFFE=_F (TOUT= “OUI”, MATER= MA),
                  AFFE_VARC=_F (NOM_VARC='NEUT1', CHAMP_GD=CHYOUNG),
                  );

Question 1 :
step (6) is not clear to me. we define a new variable "NEUT1", it's value are (-1.E-9, -1.E-9, 1.E + 9, 1.E + 9), what do these values correspond to ? are they just defined on a range corresponding to the values of "YOUNG_Y"?

Question 2 :

Is there another way of simpler processes using DEFI_FONCTION ? for example by defining a function “func_E” which correspond to the values of young modulus according to the geometrical parameter “X” with a linear interpolation at the nodes :

func_E = DEFI_FONCTION(identifier='4:1',
                       INTERPOL=('LIN', ),
                       NOM_PARA='X',
                       PROL_DROITE='CONSTANT',
                       PROL_GAUCHE='CONSTANT',
                       VALE=(0.0, 6.8, 0.05, 6.8, 0.1, 6.8, 0.15, 6.8, 0.2, 6.8004, 0.25, 6.801, 0.3, 6.804, 0.35, 6.8125, 0.4, 6.83, 0.45, 6.86, 0.5, 6.9, 0.55, 7.0, 0.6, 7.125, 0.65, 7.33, 0.7, 7.65, 0.75, 8.12, 0.8, 8.8, 0.85, 9.91, 0.9, 11.6, 0.95, 14.2, 1.0, 18.48))

Regards

#6 Re: Salome-Meca usage » Singular matrix (MFRONT behaviour law) » 2020-02-20 09:42:32

Thank you for your reply.

yes, I tried my behavior law on mtest and it works well!
it is when I use it on an element in salome_meca that I have this kind of error:

! Problème : la matrice est singulière ou presque singulière :                                                                 !
!   Lors de la factorisation de la matrice, on a rencontré un problème                                                    !
!   (pivot nul ou presque nul) à la ligne 53 qui correspond au degré de liberté donné ci-dessus.        !

Regards,

#7 Salome-Meca usage » Singular matrix (MFRONT behaviour law) » 2020-02-19 17:13:58

kadred
Replies: 2

Hello

I need your help !!

my model is a cube (10 * 10 * 10 mm), on which I make a displacement following OZ (FACE_IMPO : DZ=0.1), I carried out of a linear calculation + a nonlinear calculation with ELAS_HYPER, I did not have any problem.
When I use the same model with MFRONT behavior law, I have this problem:

! Problème : la matrice est singulière ou presque singulière :                                                                 !
   !   Lors de la factorisation de la matrice, on a rencontré un problème                                                         !
   !   (pivot nul ou presque nul) à la ligne 936 qui correspond au degré de liberté donné ci-dessus.

I took a look at the forum:
code-aster.org/forum2/viewtopic.php?id=20715 (loading is incremented)
code-aster.org/forum2/viewtopic.php?id=21056 (no double knot)
On the forum, often the problem is posed when using contact (DEFI_CONTACT), this is not the case here!
I have already checked the boundary conditions!

Could someone please tell me a little more?

Thank you