problems with contact between edges

[Anonymous]

Well, I managed to simulate the same problem in the stress analysis in the inventor and the model needs to perform this movement

however, I can't simulate on nastran because of the contacts. In the stress analysis of the inventor, when he locates the thin bodies, he already makes automatic contacts.

When I try to perform the same process, it creates the medium surfaces, but it does not create the automatic contacts and when I select the automatic contacts option, it does not identify contact and I am not able to create the contacts manually.

in the stress analysis in the inventor, he selects the edges of the elements and places them as fixed.

When I try on nastran, I can't reproduce the analysis.

[Roelof.Feijen]

Hi @Anonymous ,

In this case, the only thing Nastran needs is a surface model.

So create a surface model in Inventor. Use the Shell Idealization. 

If the edges are bonded turn the option for Continuous Meshing on.

That should give you the same results as in Inventor Stress Analysis.

If not, please attach your file.

[Roelof.Feijen · Accepted solution]

Hi @Anonymous ,

I tried to create something similar with Inventor Nastran. Take a look at the screencast below. Hope this helps.

[Anonymous]

Thanks for the help, but I still haven't managed to solve my problem with the nastran inventor. In fact, your tips were very important to adjust my model and I am very grateful for that.

Speaking a little more about my problem, here are some screenshots that can help you understand and help me.

[Roelof.Feijen]

Hi @Anonymous ,

You have an opening between the top and the bottom faces because you used the midsurface command.

In my video I created that midsurfaces upfront the simulation. The midsurfaces that I created do connect on the edges. In that case I don't need a contact.

Inventor Stress Analysis als generates a contact between the opening you have in your model, based on the Shell Connector Tolerance.

To get the same in Inventor Nastran you will need to add a Offset Bonded contact between the openings.

Hope this helps. If not, please attach your file to this post.

[Anonymous]

Again, thank you very much for your help.

I tried to do it the same way you did. I created the shell and simulated offset. As shown in this screenshot.

Here is the file, if you can take a look and check if I did it correctly, I am very grateful for the help.

[John_Holtz · Accepted solution]

Hi @Anonymous 

I see that you have results, there are no warnings in the analysis, and the results (4.96 mm displacement) match the results you got with Inventor Stress Analysis (5.03 mm).

Do you have some question about the analysis?

Here are a few comments on the previous discussion.

1. In your original Nastran analysis, the midsurfaces have a gap between them at the ends. You need to create a manual contact. "Auto" contact detects two surfaces that are touching (in the "same plane") and creates a contact pair. Since the original model did not have two planes that were touching, the "Auto" command would not create anything.
2. The dialog that you show where you set Offset Bonded contact and 0.1 tolerance does nothing on its own. That input is used when you use the "Auto" contact command on the ribbon. (The contacts created by "Auto" use the type of contact specified in the "Options" dialog that you show.) Since the Auto command would not find anything in contact, your offset bonded setting does nothing in this model.
3. Your testedois.ipt model does not need contact. You have a single part and all surfaces are connected together. The mesh is continuous and matching around the perimeter, so all of the faces are connected together. Contact is only necessary when the mesh is not matching (not continuous) between different parts or faces. This occurs when you have an assembly of parts, or when there is an intentional gap between pieces of a one-part model. (Inventor can also create multiple solid "bodies" in a part file; Nastran interprets these as separate pieces, so contact is needed for them also.)

Let us know what questions you have. Be as specific as you can.