Meshing surfaces that should bond problem

[Anonymous]

Hello,

I am having some problem getting two surfaces that should bond to do just that. This is a problem where I have to mix solids and shell elements, so what I have done is basically to create solids in Inventor (for some reason, Algor can't import surfaces from inventor) and then manually selected each of the surfaces to be meshed manually, while leaving the solids intact. So I want the surface part (part 30) to bond with the solid part (Part 20 in my image). The distance between these surfaces is zero, so I don't see the problem here. I have the exact same situation at the other end of the part, but there is no problem here. I can't figure out what's wrong and have tried tweaking the mesh matching tolerance, but to no avail.

Any help would be appreciated

Thanks

Björn

[xli]

Would you please tell what exactly you are matching:

(1) a shell part's side (not the edge of shell structure) matching to solid element part's surface or another shell element's side? or,

(2) shell's edge matching to surface of solid element part or shell element part's surface?

That would likely help diagnosing of what exact problem you have. Since such matching needs both sides have matched nodes, i.e. same mesh, so it involves meshing of both parts and part-matching. If one side is solid, it often is a delayed solid-meshing that has some odd case would need to fix surface-mesh etc.... which often cause part matching problems.

Anyway, tell us part20 and 30 is what kind of element types. Or attach the model would be a better way to tell all, I would let our meshing expert take a look. Thanks,

-xli 

[Anonymous]

Hi, Xli

I am trying to match a shell part's side to the solid element part's side. Part 20 is a strip of solid elements, and part 30 is made up of shells. What I want to achieve is (see attached picture) to connect these two together.

I will ask our customer if it is ok to share the model with you. I sure hope so, since it would make things easier.

[Anonymous]

Xli, I have been allowed to share the model with you. Do you have any ftp-server where I can upload an archive file? Please remember that it's confidential customer information.

Thanks

Best regards

Björn

[xli]

Björn, please let me (xiaogang.li@autodesk.com) know your email address, I will give you a ftp to upload the model for me. Thanks.

-xli

[Anonymous]

Xli,

I have sent you an email now.

Thanks

Björn

[xli]

Björn,

Got your model. The part matching is in a rather complex situation. I think I know the difficulty reason: shell part 6 and shell part 19 are overlapped. Without part 6, part 19 matches both brick part 22 and 24, and shell part 7 outside matches brick part 24 from other side OK. By activating part 6, the meshes will lost connection to 19 and 22,24 etc...

So do you really want that overlapped part 6 and part 19 fully bonded? That seems the problem for our mesh matching to do. I will seeking our meshing expert's advise for possible solution if he has.

-xli 

[Anonymous]

Hi, Xli

I'm terribly sorry, I had made a mistake in the model I uploaded. Surfaces 6 and 19 are not supposed to overlap. The problem with this model is that it's so thin, so deciding which surfaces to exclude from the mesh is easily mistaken. Anyway, Now it should be correct (named the file test_support2.ach). As you say, I would guess a lot of problems comes with surfaces overlapping. For example, surfaces 19 and 21 are supposed to lie in the same plane (this saves time when working with the CAD model). I guess this could also create problems?

If your mesh expert does not have a solution, then I guess I will have to manually separate the surfaces in the CAD-model. In any case, thanks for your help. I really appreciate you taking a look at this.

Best regards

Björn

[xli]

Bjorn,

Well, probably you are asking something else that will based on physics you want to simulate. I will check new model you sent. And I have asked the question to our meshing expert, the way to overcome that overlapping difficulty is to turn on "Use virtual imprinting" under meshing UI, options:Model:General:default meshing options. There is another check box, use imprinting within parts, you probably need to keep it off as you said to keep parts not bonded from sides. See if it will help you, good luck!

-xli

[Anonymous]

Thanks. I tried checking the Virtual Imprinting box, but it didn't help. I guess it's all too complex to mesh. I will go back to the basic CAD model and do some changes.

Thanks for all your help.

Best regards

Björn

[xli · Accepted solution]

Björn,

You are welcome. I actually tried your model 2 last night. With imprinting part 6,19,21 it seems ok. The match between them and part 22, 24 looked ok (I roughly checked only). But when I activated all parts meshing got other problem due to part 8 etc., which I think is due to aspect ratio in brick element is too high (too thin). So by setting model mesh size finer, ~30% mesh actuallly finished. I then blankly went to analysis without check details through those constraints and boundary condition because I don't know what you want to get from this model. The model defineitely need fine turning up to obtain converged if mesh is correct. Attached is a very initial steps results that might help your figuring out meshing is ok or not.

It is up to you to keep working on this model or not. Here is my idea that probably is similar to yours: changing geometry of part6 as (part6 - part19); and add cut off portion as a new part; then meshing part19 and copying its mesh to new part and part21, which gives you three identical meshes. You probably still need to turn down aspect ratio that will make nice finer mesh in bricks regions. Good luck.

Regards,

-xli

[Anonymous]

I think it would be easiest for me to modify the CAD geometry and make a new model. If I encounter any more problems I will let you know.

Best regards

Björn