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Joining Edges of Shells to Surfaces of Shells

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Message 1 of 4
Chris_Dunlop
823 Views, 3 Replies

Joining Edges of Shells to Surfaces of Shells

Hi everyone,

 

Currently having some problems with determining the contact tools to use for joining my shelled structure together.

 

 

The automatic constraint tool seems to not work, even when I specify the contact type to offset bonded with 1.2x the distance from the edge to surface. When I run the analysis I get the error of T2135 and within the help, it isn't quite clear how to stop this from happening as it directs to the main Nastran help section, not In-Cad.

 

However, I then tried to specify the contacts manually using the surface to edge, as generally the sections of the girder are but welded or seem welded.

 

I need to use shells as I need to determine the buckling load of the girder and assess the reduction in the buckling from the unstiffened to stiffened section.

 

I have attached some photos showing the section and the mid-surface planes used for the shell elements.

 

Thank you for the help, the questions I've asked already have been answered and have gotten me to where I am with this model 🙂

 

 

 

 

 

Main section (1).JPGMain section 2.JPGMain section 3.JPG

 

3 REPLIES 3
Message 2 of 4
John_Holtz
in reply to: Chris_Dunlop

Hi @Chris_Dunlop

 

Let me make sure that I understand your model.

  1. You have a solid model (not a surface model), and in InCAD you are using the "Prepare > Midsurfaces" command (or "Find Thin Bodies"). So, the parts are separated by half the thickness of the plate element. Is this correct?
  2. There are two "automatic" contact commands, so one may work in this situation and the other may work in a different situation.
    1. The "Contacts > Automatic" command will inspect the CAD model (the surfaces created by the Midsurfaces command) and create branches in the browser for each pair that it finds. I do not know for sure, but my guess is that this command only detects surfaces that are "co-planar". It may not find edges that lie in the plane of another surface.
    2. The "Contacts > Manual > Auto" will inspect the Nastran file during the analysis to find contacts. (If you do not use the "Specify Contact Regions", it will search the entire model.) I created a super-simple model that looks like yours and used this "Auto" contact with "Offset Bonded" contact. This worked. Take a look at the attached model "stiffened plate.zip" to see what I did.


John Holtz, P.E.

Global Product Support
Autodesk, Inc.


If not provided already, be sure to indicate the version of Inventor Nastran you are using!

"The knowledge you seek is at knowledge.autodesk.com" - Confucius 😉
Message 3 of 4
Chris_Dunlop
in reply to: John_Holtz

Hello John!

 

I shall do the listed methods below again to see if anything I've done was wrong.

 

I will add though, I made the mid-surfaces within the Inventor simulation tool, as this was much quicker than the one built into In-Cad. 

Would this of made a problem?

Message 4 of 4
John_Holtz
in reply to: Chris_Dunlop

Hi Chris,

 

You mentioned that you had also used the Inventor simulation tool to create midplane surfaces and wondered if that had some affect on the Nastran InCAD analysis.

 

I do not know for sure, but I suspect that the data is stored separately, so nothing done in the Inventor Stress environment should have any affect on the InCAD environment.

 

Let us know what you find out.

 


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John Holtz, P.E.

Global Product Support
Autodesk, Inc.


If not provided already, be sure to indicate the version of Inventor Nastran you are using!

"The knowledge you seek is at knowledge.autodesk.com" - Confucius 😉

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