Your Feedback on Code Aster !

johan

Thanks for the reply. I see Salome -Meca as an integrated suite of programs and certainly hope that the people responsible for Salome would read my post.

Thanks for the orientation clarification.

Regarding linking elements, I found what I was looking for in LIAISON_MAIL. (I should have read the new U4.44.01 gitlab before I made the comment.) Having found this I thought I will test it on a simple model, just to be confronted with a new surprise: AFFE_CHAR_MECA does not apply the load where I intended it to be. The message is:

MAILLE : M97
MAILLE : M98
MAILLE : M99
MAILLE : M100

║ <EXCEPTION> <MODELISA6_96>
║
║ les 4 mailles imprimées ci-dessus n'appartiennent pas au modèle
║ et pourtant elles ont été affectées dans le mot-clé facteur : FORCE_ARETE

while my intention was to apply it to edge group "Load" elements 335 to 338.

My first question always is "What am I doing wrong." and in a real simulation it takes a lot of time and effort to find an alternative, if there is one, to get past the error. The alternative is that it confirms my first point.

I have used Salome_Meca 2023 with the default version of Code Aster. I attach my mesh and command files and will appreciate comments on it . (I can't upload the file, I will post a link to it.)

johan

The link to my file is:
https://www.dropbox.com/scl/fo/uhbe6j636amnl2qbqmar6/AD6xO44SagMKFA7KEtEeaWY?rlkey=jl6tj9q3pf6r8s8qp7cs6bsb1&dl=0

johan

k_zurawski

It is a long time since I have last looked at Strand7,but will do so again. I am also using Mecway, which I find very good for small models and it is very user friendly.

k_zurawski

johan try prepomax as well.

AsterO'dactyle

HEllo,

If you have specific questions, it is best to make a new post.

COMPOR1_47 => The finite element formulation does not allow for large rotations, as specified in the theoretical documentation (r3.07.05). They must remain less than 360°.

contact + arc-length: This is a very difficult theoretical problem. To my knowledge, the only case that can be dealt with without too much difficulty is penalized contact (see the work of Wriggers).

Do you know if Simvia is working on resolving those issues?: The code_aster development team has no connection with SIMVIA; you'll have to check with them. I believe they have released a version on Docker.

@johan : When applying a load (NEumann), a finite element support is required (weak formulation). In code_aster, this means that the meshes to which you assign these loads must be in the MODELE. You must therefore assign the group "Load" to which the load is applied in AFFE_MODELE.

k_zurawski

AsterO'dactyle COMPOR1_47 => The finite element formulation does not allow for large rotations, as specified in the theoretical documentation (r3.07.05). They must remain less than 360°.

I'm getting this error even if rotation is around few degrees.

johan

AsterO'dactyle

Thanks for the reply again, but I think there is a bit of misunderstanding.
Edge group "Load" is created in the mesh module, is recognized in Aster Study and shows correctly in "Mesh groups involved" in AFFE_CHAR_MECA. It appears to me that the element assignment has changed somewhere before it got to Code Aster.
I have never created a mesh group in AFFE_MODELE simply because it is so easy to do it in the geometry or mesh modules.

AsterO'dactyle

k_zurawski

Yes, the message is systematic because it cannot measure rotations since... they are poorly modelled by the element.

It's going round in circles!
We could change it to simple information instead of an alarm.

AsterO'dactyle

Yes, misunderstanding

model = AFFE_MODELE(identifier='2:1',
AFFE=(_F(GROUP_MA=('Solid','Load' ), <===== HERE
MODELISATION='3D',
PHENOMENE='MECANIQUE'),
_F(GROUP_MA=('Plate', ),
MODELISATION='COQUE_3D',
PHENOMENE='MECANIQUE')),
MAILLAGE=mesh1)

(I don't know is Load is on 3D or COQUE_3D)

johan

AsterO'dactyle
Thanks again.
I should have been more specific: I need to connect COQUE edges to Solid faces. It appears that one can only connect coque faces to solids?

My commands now are:
model = AFFE_MODELE(AFFE=(_F(GROUP_MA=('LinkF', 'Solid'),
MODELISATION='3D',
PHENOMENE='MECANIQUE'),
F(GROUP_MA=('Load', 'LinkE', 'Plate'),
MODELISATION='COQUE_3D',
PHENOMENE='MECANIQUE')),
DISTRIBUTION=F(METHODE='SOUS_DOMAINE',
PARTITIONNEUR='METIS'),
INFO=1,
MAILLAGE=mesh1,
VERI_JACOBIEN='OUI',
VERI_NORM_IFS='OUI')

and
mecach = AFFE_CHAR_MECA(DOUBLE_LAGRANGE='OUI',
FORCE_ARETE=F(FZ=-16.7,
GROUP_MA='Load'),
INFO=1,
LIAISON_MAIL=F(ELIM_MULT='OUI',
GROUP_MA_ESCL='LinkF',
GROUP_MA_MAIT='LinkE',
TYPE_RACCORD='MASSIF_COQUE'),
MODELE=model,
VERI_AFFE='OUI',
VERI_NORM='OUI')

╔════════════════════════════════════════════════════════════════════════════════════════════════╗
║ <EXCEPTION> <PROJECTION4_55> ║
║ ║
║ Il n'y a pas de mailles à projeter ou en correspondance. ║
║ Dans le cas de l'utilisation de AFFE_CHAR_MECA / LIAISON_MAIL, les mailles maîtres ║
║ doivent avoir la même dimension que l'espace de modélisation : ║
║ - mailles volumiques pour un modèle 3D ║
║ - mailles surfaciques pour un modèle 2D ║
╚════════════════════════════════════════════════════════════════════════════════════════════════╝

k_zurawski

AsterO'dactyle Yes, the message is systematic because it cannot measure rotations since... they are poorly modelled by the element.

Could you tell more about that? Is it related to mesh quality or some inverted elements I didn't notice?

k_zurawski

johan to do that you may use rigid connection - LIAISON_SOLIDE, which is probably the closest to RBE2 from Nastran. Prepare two groups, one on the face of the solid and second on the edge of the shell you'd like to connect, then list them both, for example:

Rigid=AFFE_CHAR_MECA(MODELE=Model, LIAISON_SOLIDE=_F(GROUP_MA=('SHELL_EDGE','SOLID_FACE',),),),

Then you also call it in calculation like any other BC in EXCIT.

Result=MECA_STATIQUE(MODELE=Model, CHAM_MATER=MatField, CARA_ELEM=Cara, EXCIT=(_F(CHARGE=fixed,), _F(CHARGE=Rigid,), _F(CHARGE=Moment,),),)

Shell has 6 DOF, solid 3 DOF - LIAISON_SOLIDE is the simplest way to transfer bending moment to the solid model.

johan

k_zurawski
Thank you Krzysztof, I never thought of that one. Will try it.

Phoenix

Hi,

Code Aster & Asterstudy both are great softwares, and I like them so much. Meanwhile, I like humorous French people, I love romantic France, though I know little about the French language. Now, I've got to know LIRE_MAILLAGE = READ_MESH. I think if there is an version of Asterstudy with operators named with the English language, it will be quite easilier to learn & use, and the number of the users of Code Aster & Asterstudy will increase dramatically.

Best wishes!

Phoenix

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