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Air Spring model - 3d shell edges mixture failure- Help ??

Air Spring model - 3d shell edges mixture failure- Help ??

Air Spring model - 3d shell edges mixture failure- Help ??

(OP)
Hi Guys,

I have prepared a model, in the best of my level's abilities for an airspring.
I have the .cae file to share for some assistance feedback.

I get the below message:

"Surfaces below have a mixture of 3D shell edges and other types. If a surface has any 3D shell edges then all of its facets must be 3D shell edges.

_PickedSurf67

- I guess surf67 is the surface that causes the issue - but I don t know how to figure where it is in the assembly.


I would really appreciate some help to make my model run - it is a draft model so I don't particularly care for actual results. I m more keen on making the simulation work at least kinematically.

RE: Air Spring model - 3d shell edges mixture failure- Help ??

O_Giannis

There must be .odb file created after unsuccessful run by Abaqus. Open it in Abaqus visualization module. Go to display group=>Surface=>internal sets=> check for _PickedSurf67

I would recommend to create surfaces sets with "name" for easy identification when warning or errors are displayed.

Quote (O_Giannis)

Surfaces below have a mixture of 3D shell edges and other types. If a surface has any 3D shell edges then all of its facets must be 3D shell edges.

Avoid selecting 3d shell edges and shell surfaces or other geometric entities in same surface set. This error is due to selecting mixed facets in the surface sets.

RE: Air Spring model - 3d shell edges mixture failure- Help ??

This surface likely belongs to some constraint. When you find it and proceed to redefine the constraint, be careful what kind of geometry you pick. A selection filter can help you avoid such mistakes.

RE: Air Spring model - 3d shell edges mixture failure- Help ??

(OP)
Hi both,

I have found the internal surface that refers to _pickedsurf67, but i have not created this one from the surface menu.
I use it for the fluid cavity Or for a constraint as correctly mentioned. A fluid cavity needs surfaces as interaction, so i don t know how i can avoid it. If anyone would have some time to have a more experienced look on the subject it would be of great help. As said I consider myself a beginner.

RE: Air Spring model - 3d shell edges mixture failure- Help ??

O_Giannis

You have picked this surface (for load application, interaction or constraint) and Abaqus internally names it (since you haven't given any name to it) for identification purpose. Try redefining surface with proper name now and with proper entities. May be you have accidentally selected shell edges along with surfaces or shell surfaces along with shell edges.

RE: Air Spring model - 3d shell edges mixture failure- Help ??

(OP)
Should I instead create surface sets and assign them without manually choosing them?
Also, due to the design of the sleeve, there are some fillets that might create these edges. Can I avoid that? Should I partion them?

thanks in advanceeee!

RE: Air Spring model - 3d shell edges mixture failure- Help ??

Both approaches are good as long as you select the proper types of geometric entities. It’s a matter of convenience if you choose the first way (creating named surfaces before using them in constraints) or the second one (relying on automatic creation of surfaces picked when defining constraints). As I’ve mentioned before, a selection filter can help you avoid problems.

RE: Air Spring model - 3d shell edges mixture failure- Help ??

Yes. As FEA way suggests you can apply selection filter when selecting surface/or any geometric entities.

Also, I suggest to post Abaqus related questions in forum799: DASSAULT: ABAQUS FEA Solver since its dedicated forum for Abaqus. Here you can put general question related to FEA.

RE: Air Spring model - 3d shell edges mixture failure- Help ??

(OP)
Thank you both for your answers, I will try to play around with the model a bit more, but the way I see it, since I lack of the experience to do changes, I ll probably end up with deleting more of the things and redo them.

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