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#1 Re: Code_Aster usage » Contact with SIMO_MIEHE » 2022-01-29 17:42:25

Hi there,

thanks a lot for the multiple replies first of all. I keep investigating on this issue which I have not completely solved. Currently I am working on the simplified model I put here and I managed to make it converge. I had to modify the whole model substantially. In particular:

1) I had to add several springs (DIS_TR). They stabilise a lot the simulation and, even if they affect the results a little bit, I noticed you can't make it without them

2) I had also to work on the mesh. I very much refined the mesh (keeping under control the quality)

With this two updates I managed to make the SIMO_MIEHE material converge (with a little time step). In the coming week I try the same solution on the big model I have and I really hope this works.

In any case, we are talink of VERY slow simulations: on my mesh which are something like 1.000.000 nodes it could take more than 24/48 hours to get the results ... and this is not very good either.

#2 Re: Code_Aster usage » Contact with SIMO_MIEHE » 2022-01-26 22:09:07

AsterO'dactyle wrote:

Hello,

With contact, PREDICTION='ELASTIQUE" is a good idea

Hi, thanks for the hint. I tried that but with no luck...

#3 Re: Code_Aster usage » Contact with SIMO_MIEHE » 2022-01-26 20:52:50

And the attachment I forgot in previous post

#4 Re: Code_Aster usage » Contact with SIMO_MIEHE » 2022-01-26 20:48:34

Attached you find a mesh and a message.dat file in a very much simplified situation with a small drawing representative of the situation.

I start being a bit desperate about this case as I worked on it for 10 days in order to make it converge and still I didn't manage.

#5 Re: Code_Aster usage » Contact with SIMO_MIEHE » 2022-01-26 17:35:22

piotr.kozlowski wrote:

Is it a displacement or force-controlled problem?
I don't have experience with the elements you are using there for the gasket, but if the elastic model converges then I would look closer at the material properties. In particular the definition of the tangent modulus. Have you tried to increase the tangent modulus for the elastoplastic material?

It's a force controlled problem. I tried that as well, but so far I have had poor results also using this [or better, the simulation is still running but it is very long and so I can't tell you if this can be a solution ...].

Are there other modelling possibilities you could reccomend? I didn't use shell as I am not sure whether shells can be compressed in between two surfaces. Do you know if this is possible?

#6 Re: Code_Aster usage » Contact with SIMO_MIEHE » 2022-01-26 16:48:27

Hi piotr,

thanks for your reply. About your points here you are my answers:

1. I would try to change the material to linear elastic formulation and check if the analysis converges.

-> yeah, I confirm that linear analysis converges towards a result. The experimental data are not coherent with that and for this I need to turn on plasticity

2. I would also try to ramp the "squeezing" at a lower rate.

-> On this term I think I tried everything. I tried lowering this rate both by adding time steps and reducing the FONC_MULT

3. How many elements does the gasket have through thickness? Can you make a snapshot showing the contact region of the gasket/housings? Try changing the contact do bonded ad see if it converges.

-> in the most recent I placed 3 layers of extruded tetrahedron as in the attached picture. I can add some more, but the computational time increases a lot (it's several hundred thousands cells). About maing the contact bounded it is not possible as at the beginning the gasket surface is not flat, it becomes flat after the pressure from the housing and the cover.

#7 Code_Aster usage » Contact with SIMO_MIEHE » 2022-01-25 10:26:02

rupole1185
Replies: 12

Hi there,

I have a problem to be handled (for which I can't share the mesh as it's under SLA with a client, but I try my best to make you understand it). The situation I am simulating consists of a gasket which is squeezed in between a housing and a cover. The gasket is made of steel which, due to the squeezing, goes into plasticity zone.

Everything is made of extruded prisms (so 3D modelling). To simulate this I made obviously a contact as follows:

contact = DEFI_CONTACT( FORMULATION='CONTINUE', RESI_GEOM=0.01, MODELE=model,
                           ZONE=_F( GROUP_MA_ESCL=( contact_slave_surface, ), GROUP_MA_MAIT=( contact_master_surface, ),), )

I made several attempts using STAT_NON_LINE but they all failed. For STAT_NON_LINE I use this configuration:

         stat2 = STAT_NON_LINE(
                CARA_ELEM=elemprop,
                CHAM_MATER=fieldmat,
                CONTACT=contact,
                EXCIT=loadr,
                COMPORTEMENT=comportement,
                INCREMENT=_F(LIST_INST=times, INST_FIN=listr.Valeurs()[1], ),
                 NEWTON=_F( MATRICE='TANGENTE', PREDICTION='TANGENTE', REAC_INCR=1, REAC_ITER=1, ),
                ARCHIVAGE=_F(PAS_ARCH=SaveFreq),
                 CONVERGENCE=_F(ITER_GLOB_MAXI=80, RESI_GLOB_RELA=1e-4,),
                MODELE=model
                )

where comportement is:

                        comportement=(_F(TOUT='OUI',
                                         RELATION='ELAS',
                                         DEFORMATION='PETIT',
                                         RESI_CPLAN_RELA=1.E-06,
                                         RESI_INTE_RELA=1.E-06,
                                         ITER_INTE_MAXI=20,
                                         ITER_INTE_PAS=0,
                                         ITER_CPLAN_MAXI=1,
                                         SYME_MATR_TANG='OUI',
                                         PARM_THETA=1.0,),
                                      _F(GROUP_MA=('LAY_3D_1', ),
                                         RELATION='VMIS_ISOT_LINE',
                                         DEFORMATION='SIMO_MIEHE',
                                         RESI_CPLAN_RELA=1.E-06,
                                         RESI_INTE_RELA=1.E-06,
                                         ITER_INTE_MAXI=20,
                                         ITER_CPLAN_MAXI=1,
                                         SYME_MATR_TANG='OUI',
                                         PARM_THETA=1.0,),)

But all the attempts I made using STAT_NON_LINE fail with an Error like this:

__________________________
<Erreur> Échec dans l'intégration de la loi de comportement

<Action> On essaie de découper le pas de temps.
          On utilise la découpe manuelle.
          Découpe uniforme à partir de l'instant < 0.000000000000e+00> en <2> pas de temps.
                    (soit un incrément constant de < 8.333333333333e-03>)
          Le nombre maximal <2> de niveaux de subdivision est atteint.
<Action><Échec> Échec dans la tentative de découper le pas de temps.
__________________________

I tried then to use DYNA_NON_LINE with a similar configuration and the process gets a bit better but I am forced to use an incredibly small time step (i.e. 1E-3) which means I may get results in a very long time or, if I am less lucky, the simulation gets stuck after several hours with the same error mentioned before.

I know that without mesh it's difficulto to help, but if someone have had experiences about this maybe he can try and share them!

#8 Re: Code_Aster development » Possibility of Cloud-based Service around Code-Aster » 2021-03-27 19:55:52

Hi there,

I am member of the Italian community of CodeAster. In Italy there is a small start-up which provides CloudHPC, a platform to run CodeAster on the cloud as you said. I might suggest that by checking their website: cloudhpc.cloud


sb1966 wrote:

Dear All,
I wonder, if there is any plan for introducing Cloud-based service around Code-aster/Salome-Meca in (near) future.
I believe, cloud based service is going to be the trend in real life CAE in near future. This is because, I think, the infrastructure and the expertise required for providing/maintaining the HPC resources necessary for realistic simulation of complicated industrial problems are not easily or widely available. Also, it won't be feasible for every one to acquire such resources.

Some companies like Onscale.com are already in the show, by introducing cloud-based simulation platform subscriptions. Keeping in view the multiphysics capabilities of Code-aster, I think it is one of the most suitable candidates to be introduced as a cloud based simulation platform.

I do hope, EDF or other companies working around Code-aster would ponder over the matter and come forward for fulfilling the industrial needs in this regard. I am sure, it would be a win-win situation for both the service provider and the subscribers.

With regards

Sukumar

EDIT: I have come across SimScale which is a cloud based HPC service and it uses Code-aster for Mechanics simulation. I am yet to explore it though.

#9 Re: Code_Aster usage » Heat transfer with ECHANGE_PAROI » 2017-10-03 14:02:53

dezsit wrote:

Dear Community,

I would like to rise up an old problem again, because I have not seen progress in it. (Or we missed something during the years?)

So my question is: Is it planed to handle the thermal contact (more precisely thermal resistance between walls - ECHANGE_PAROI) on based on a master-slave pairing approach? (I suppose the pairing algorithm of for example LIAISON_MAIL could be used easily in this case, which is already present in the AFFE_CHAR_THER operator). We could save a lot of partitioning/meshing work with that.



Thank you
and
Best regards,
DT.

I joing with the same problem ... so if there are two of us probably it is more likely the development is made!

#10 Re: Code_Aster usage » RAM usage in Code Aster » 2017-09-08 16:58:16

Thanks a lot for your help. I am now trying with your suggestions and I will let you know if I manage to solve my problem.

Just one more question: the slides you linked are actually in french, I looked for the english version but I couldn't find them ... Do you know if there is a translation?

#11 Code_Aster usage » RAM usage in Code Aster » 2017-09-08 11:08:32

rupole1185
Replies: 4

Hello everyone. I am experiencing a very high RAM usage in Code Aster (v12). There might be a number of reason for that obviously, but I would like to know a bit more about the configuration I use and whether that is actually optimal for my case.

I use a volume mesh with TETRA10 elements (second order). I made several tests for various mesh dimensions (from 0.1M to 3.5M elements), but the problem is the RAM required to run the simulation. I have 60GB available, and already all of them have been used when the mesh reaches 1M elements .. now I am not an expert, but the RAM used by the solver is more than 600 times the mesh dimension.

I would only like to know from you that the settings I am using are appropriate and, eventually, what I can do to improve this.

Thanks to everyone for the help

#12 Re: Code_Aster development » Plot residuals, Follow state simulation » 2017-04-13 21:57:41

I am also very interested in this topic ... if anyone could reply!

#14 Re: Code_Aster usage » [SOLVED] Polyethylene tank - GROT_GDEP with 3D modelling » 2017-04-13 21:45:38

After two full days on the code I found what probably is a common mistake. I am going to write it down for newbies like me!

Basically, STAT_NON_LINE, when non linear behavior is assumed - such as GROT_GDEP - needs to iterate towards the final configuration. I had to insert time steps (DEFI_LIST_REEL and DEFI_LIST_INST) to define such iterations through time and, meanwhile, I supposed the pressure load to grow proportionally with time (DEFI_FONCTION and FONC_MULT=FORCE).

Once this is known, it's just a matter of finding the best match between number of iterations ...

I attached my new comm file as a reference.

#15 Code_Aster usage » [SOLVED] Polyethylene tank - GROT_GDEP with 3D modelling » 2017-04-12 09:20:05

rupole1185
Replies: 2

Hello everyone!

I would like to get some help with a simulation of mine.

In this case, we are simulating a sort of tank (unluckily I can't share with you all the geometry of the tank) with an internal pressure of 0.5 Bar.
I am using a 3D models (coque is not possible) and, considering it is made up by Polyethylene I would like to use a large displacement comportment (GROT_GDEP).

I produced the attached .comm file, but, when I run the simulation it basically doesn't converge so I don't get results.

I hope some of you can help me with this particular topic!

#16 Code_Aster usage » Import pressure from Paraview to Code-Aster » 2017-02-18 00:09:46

rupole1185
Replies: 0

Dear all,

I am writing you a relatively common problem for aster i suppose.
Basically I have results of a STEADY CFD simulation available in Paraview (Ensight format)

Now I would like to export the static pressure out of the CFD results and use it as boundary for a FEM simulation in aster.

A small remarks: the CFD and FEM meshes are not the same.

I read a bit around and I found that a composition between LIRE RESU and PROJ_CHAMP can do the job ... but so far I failed so badly!

Can anyone help me a little bit?

#17 Re: Code_Aster usage » Multi body static simulation » 2016-11-09 10:33:09

Good news! I now have solved the problem!

I had double nodes in my mesh and with salomè i deleted them (as specified here: http://docs.salome-platform.org/latest/ … page.html).

I hope this may help other people with similar issues!

#18 Re: Code_Aster usage » Multi body static simulation » 2016-11-09 10:03:07

There is an update.

I discovered that the mesh groups had problems in my previous posts. I managed to fix them and now my mesh has:

1) 3 different "solid" groups used to apply the three materials
2) 2 surfaces to apply boundary conditions

Now the contact surfaces are no more present and basically two solids now share nodes on common surfaces.
My problem is that I get liability and singular matrix now ...

Nobody can help me?

#20 Code_Aster usage » Multi body static simulation » 2016-11-08 10:05:52

rupole1185
Replies: 3

Dear all,

thanks in advance for your reply to be (which I know there will be :-D).
I want to run a static simulation with three bodies, each of which is composed by a different material (thus different E, nu).

I gave to salome a step file with three bodies, created three volumes and all the "contact" surfaces. What I want to do on the contact surfaces is forcing the same displacement on both the surfaces. For this I created the attached MESS file ... but regardless my efforts so far I didn't get any result.

Can anyone help me?

#21 Code_Aster usage » code retour WRITDR : -4 » 2016-10-14 08:36:04

rupole1185
Replies: 0

I am getting the following error:

####################################################################################################################

   !-----------------------------------------------------------------------------------------!
   ! <EXCEPTION> <JEVEUX_40>                                                                 !
   !                                                                                         !
   !      Erreur criture de l'enregistrement 4305 sur la base : VOLATILE 0                  !
   !      code retour WRITDR : -4                                                            !
   !      Erreur probablement provoque par une taille trop faible du rpertoire de travail. !
   !-----------------------------------------------------------------------------------------!

tee: fort.6: No space left on device


Critre de destruction du fichier (1.00 %) associ  la base VOLATILE dpass 9.03 %
Nombre d'enregistrements utiliss : 5682
Volume disque occup              : 4439 Mo.
Nombre maximum d'enregistrements  : 62914


  Ouverture en criture du fichier ./vola.1

  Destruction du concept 'RESU'.

   !-------------------------------------------------------------------------------------------------!
   ! <A> <JEVEUX1_64>                                                                                !
   !                                                                                                 !
   !  Le volume des donnes temporaires (objets de la base Volatile) crites sur disque (3365.62 Mo) ! !  est plus de 100.00 fois suprieur au volume de donnes lues (0.78 Mo).                       !
   !                                                                                                 !
   ! Risques et conseils :                                                                           !
   !  Ce dsquilibre n'a pas de consquence sur les rsultats de calcul, il indique simplement que  !  certaines structures de donnes temporaires ont t crites sur disque et dtruites sans avoir!  t relues. C'est le cas lorsque vous utilisez le solveur MUMPS, car certaines structures de   ! !  donnes sont volontairement dcharges pour maximiser la mmoire lors de la rsolution.   !
   !                                                                                                 !
   !                                                                                                 !
   ! Ceci est une alarme. Si vous ne comprenez pas le sens de cette                                  !
   ! alarme, vous pouvez obtenir des rsultats inattendus !                                         !
   !-------------------------------------------------------------------------------------------------!

####################################################################################################################

My french is not perfect ... but am I correct assuming that I run out of space in the travail directory?

#22 Re: Code_Aster usage » Code aster from shell » 2016-06-10 13:04:08

Thanks a lot. I managed to find the book and I'll have a look at it in order to be independent!

Too kind!

#23 Code_Aster usage » Code aster from shell » 2016-05-27 16:30:33

rupole1185
Replies: 2

Dear all goodevening!

I am relatively new in code aster, at least in its usage from shell. In fact I used it quite often from SALOME-MECA (starting from a STEP file, through the meshing phase and then to the SETTINGS and RESULTS). But now, for automation reason, I would like to move to a shell scripting.

I am trying to understand the folder and files organization, i.e. I know the case.comm file with its commands as from documentation, but I don't know about:

1) Mesh file location -> from SALOME-MECA I used to get only the final result.mmed file, while I think I should import somehow a mesh. Like, I have now a UNV mesh which has to be translated ...

2) What command should I use the to run codeaster from shell? Keep in mind I am on Ubuntu 14.04 and I installed the codeaster package through the ubuntu package manager

If anyone (with great patience) is so kind either to reply or to redirect me to a guide where I can find these pieces of info I would really appreciate it!

By to everyone!