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#1 2011-01-08 16:22:09

rcbsimoes
Member
Registered: 2010-12-09
Posts: 41

mixed mesh

Hi all,

can someone point a mesh example, where both 3D and beams coexist?

i have a complex geometry, which i believe i could Analise with a simple shell and a couple of beams.

I've build a compound with a solid (future coque) and wire (future beam).
but when i try to mesh it:
1st, which hypothesis should i use??
2nd, only Netgen1D2D3D, works. (does it?). but when i do "show only" this mesh, i dont see the beam element.

i could creat 2 meshes, but how do i load them in the comm file??

rui simoes

ps. i've tried to sew it too...

ps. this code works, but... still testing.

MAILLAGE=LIRE_MAILLAGE(UNITE=20,               
                     FORMAT='MED',            
                     NOM_MED='mola',            
                     INFO_MED=1,);          
MAILLAGE=LIRE_MAILLAGE(UNITE=20,                
                     FORMAT='MED',           
                     NOM_MED='mola2',          
                     INFO_MED=1,);
ASSE_MAILLAGE... #use "collage"

not sure if i am able to affe_modele with different models (beam and shell)...
i'll post my results

Last edited by rcbsimoes (2011-01-09 13:33:37)

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#2 2011-01-09 23:32:53

Claws
Member
From: Denmark
Registered: 2009-03-23
Posts: 375

Re: mixed mesh

It's pretty straightforward to use different modelizations in aster, you just assign a model to the corresponding mesh-group (node, face or whichever). AFFE_MODELE -> AFFE for a shell and +AFFE for a beam - then you're set.

Connecting to two different types of models is a different matter though; you have to consider how they are connected. Is it 'welded' onto a single point? then you can use e.g. LIAISON_SOLIDE. If the beam/shell is an extension of each other somehow, then you should consider what LIAISON_ELEM has to offer you. It depends entirely on the structure.

Hm, I also get 'Global 1D algorithm missing'  when meshing 1D elements with either 2D or 3D elements - I haven't encountered that before, nor apparently needed it - I've used "hexa,quads, avg. length" and "Mefisto-tetra,tris, avg. length' usually - that works well with 1D elements. Let me/us know if you figure out how to do it with Netgen.

Regards,

Claus


Opensuse 15
http://www.caelinux.org/wiki/index.php/Contrib:Claws/Code_Aster

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#3 2011-01-10 01:24:06

rcbsimoes
Member
Registered: 2010-12-09
Posts: 41

Re: mixed mesh

hi,

just to make it easier i built two wires (geo) with one coincident point.
so i would connect to beams insted of a solid and a beam.

1st) i tried to read one mesh at a time, and then assemble the mesh (asse_mesh). no good, since i had only groups of nodes, and Asse_mesh requires Groupe_ma...

2nd) i tried having a affe_modele for each mesh, but it didn't work either. i couldn't really understand how to solve it. probably i cant have two models, can i??

3rd) finnaly i'm tring to affe both meshes inside one affe_modele,

problem #1, affe_modele and affe_material, they both require a mesh as input, and i have two. which one should i use??
since i can assign a modele, i supose i can use either meshes. but i get an error stating i dont have Mail1 inside Mail1...
problem #2, i cant realy understand the liason_solid. i cant state 2 group_nodes.

could you send me an mixed mesh example? or at least a link to one?
with liason solid would be great, since thats the case.

greetings
rui

Last edited by rcbsimoes (2011-01-10 01:26:02)

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#4 2011-01-10 01:58:20

Claws
Member
From: Denmark
Registered: 2009-03-23
Posts: 375

Re: mixed mesh

Awright, you shouldn't have to go through all those hoops to mix elements - you should be able to create the geometry as a compound, mesh it with either 'automatic tetrahedralization' or 'automatic hexahedralization', then have the mesh you need.

Imagine a 2D plane (X) that is connected to a beam (O) here - the Ø is in fact two nodes lying coincident - one from the plane geo, and one terminating the beam. This is the LIAISON_SOLIDE group.

xxx
xxøooo
xxx

In the attached example (what I could just find) a 3D solid cube is suspended by two cables - it shouldn't matter to you, just take what you need from the .comm file.

Let me know if something is unclear.

Regards,

Claus


Attachments:
cable2.comm.zip, Size: 30.2 KiB, Downloads: 706

Opensuse 15
http://www.caelinux.org/wiki/index.php/Contrib:Claws/Code_Aster

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#5 2011-01-10 11:13:35

rcbsimoes
Member
Registered: 2010-12-09
Posts: 41

Re: mixed mesh

thanks claws!

yesterday i couldnt do this in eficas:

LIAISON_SOLIDE=(_F(GROUP_NO='liaison1',),
                                        _F(GROUP_NO='liaison2',),),);

but i do think this should solve my problem.
i'll try to test it till the end of today. then i'll post my results.

i may have a trouble with the meshing fase, but i'll try once more.

greetings
rui

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#6 2011-01-10 13:12:53

rcbsimoes
Member
Registered: 2010-12-09
Posts: 41

Re: mixed mesh

still working... smile

any way in you example,
i thought that the "liaison1" would be a group of one node in the cable, and liaison2 a node group in the box... but it isn't, they are both in the cable.

how can CA link the models there??
or does CA analise if there are more than one node in the same place and elimimate one of them, leaving the model connected??

back to CA..
rui

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#7 2011-01-10 15:06:13

Claws
Member
From: Denmark
Registered: 2009-03-23
Posts: 375

Re: mixed mesh

No, if you look a little closer you'll notice that one node belongs to the beam and the other belongs to the cube. If you use Mesh Element Info and pick each node you see e.g. that in 'liaison1' there are two nodes: 1 and 9 -  node 1 is connected to 7 elements while node 9 is only connected to one element, i.e. it only belongs to the beam section smile

Regards,

Claus

Last edited by Claws (2011-01-10 15:09:09)


Opensuse 15
http://www.caelinux.org/wiki/index.php/Contrib:Claws/Code_Aster

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#8 2011-01-11 01:26:00

rcbsimoes
Member
Registered: 2010-12-09
Posts: 41

Re: mixed mesh

yes you are right! there are two nodes in each liaison group, one for solid one for cable. thats much better.

i'm now able to mesh the compound (solid+edge), create the link_node_group (just like you did, two nodes one in each element),
believe i understood your comm file, but still i can't run my case.

kind of weird...

every time i run the case, i dont get a resu file, and my mess files ends with a different error, like:
EXECUTION_CODE_ASTER_EXIT_3534=1
or
EXECUTION_CODE_ASTER_EXIT_3357=1
every time a different one. i wonder what does that mean.

i've re-run the postinstall.py. (though it might be a corrupted CA or SALOME), really don't know.

i'm attaching the files, maybe you can take a look.
rui

ps. cant attach the mesh... size limitation i assume. could i send the mesh to an email?

Last edited by rcbsimoes (2011-01-11 01:30:58)


Attachments:
study20.zip, Size: 3 KiB, Downloads: 684

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#9 2011-01-11 03:04:21

Claws
Member
From: Denmark
Registered: 2009-03-23
Posts: 375

Re: mixed mesh

That is indeed strange. Delete the 'flasheur'  folder in your home folder, then rerun the case from ASTK. That should generate a new set of files in ~/flasheur - your should be able to compress those and attach here.

Regards,

Claus


Opensuse 15
http://www.caelinux.org/wiki/index.php/Contrib:Claws/Code_Aster

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#10 2011-01-11 12:42:41

rcbsimoes
Member
Registered: 2010-12-09
Posts: 41

Re: mixed mesh

Hi,

deleted the flasheur and still doesnt run.
besides CA runs other cases, simpler ones.

i'll create another case and test. i'll return with news.

greetings
rui

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#11 2011-01-11 15:36:14

rcbsimoes
Member
Registered: 2010-12-09
Posts: 41

Re: mixed mesh

Hi,

created a 2 wires L shape.
created link node group  with 2 nodes (just like claus did)
created mesh
used the Liaison_solid..

it worked, after all!!!
think there was samething wrong with previous comm file.

now i'll try with my original problem.
thanks
rui

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#12 2011-01-11 18:00:48

rcbsimoes
Member
Registered: 2010-12-09
Posts: 41

Re: mixed mesh

Ok, it works. although i am not sure how the connection is made.

the problem, the reason the case would not run, nor did it emit any error (i couldnt even open the comm with eficas), aparently was due to the peaseant charge.

eficas and my code aster don't like it... dont know why.

rui

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#13 2011-01-12 12:13:00

rcbsimoes
Member
Registered: 2010-12-09
Posts: 41

Re: mixed mesh

Hi,

i've now installed new SALOME_MECA 2010.2,
PEASEANT is now working.

rui

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