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Simulation (Cosmos) 2009 and Shells

Question asked by Derek Bishop on Oct 8, 2008
Latest reply on Oct 10, 2008 by Vince Adams

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Meshing in 2009 is different than 2008. The program takes cues from the way the model is built to automatically assign a mesh.

I have a model conisting of a pipe (formed from a sweep) mounted on some brackets. I want to mesh the pipe as a shell and the bracket as a solid. It seems the program treats the whole lot as a solid.

Any suggestions? I want to avoid having to remodel the pipe as a shell.

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Vince Adams Oct 8, 2008 1:36 PM
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Hi Derek, great question! Did you take the time to review the New UI videos in the pop-up which appeared when you first started Simulation in 2009? There was one on Shell Modeling in 2009. If you no longer see this option, you can access these videos from Simulation Help > What's new... " > "Click here for an overview..."

This should clear up your questions on getting shell models from solid bodies.

Please post back if this doesn't help...

Thanks!

-- Vince
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Ian Hogg Oct 8, 2008 1:36 PM
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Hi Derek,

If the part is a solid, then by default it is treated as such. If it were sheet metal, it would have a shell representation by default (but you could toggle it to be solid).

If you want a shell representation, the best way is to either create a zero offset dirstance surface of the pipe or a midplane surface representation (offset half the distance or use the SW midsurface tool). Personally I like having separate configurations in the part to toggle between the solid representaiton or the surface representation.

In 2009 you can also use the exclude option to ignore the solid body and just account for the surface body.

Hop this helps,

Ian
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- Derek Bishop @ Ian Hogg on Oct 9, 2008 2:00 PM
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  Vince,
  
  I reviewed the video again. The model consisted of a pipe run with a few bends and a single flange. I want the flange to be meshed aas a solid and the pipe as a shell.
  
  To do this in 2009 I created another part which gets added to the assembly in which the route is mated. A shell is then created in this part and the surface thickened. I run the FEA and exclude the actual pipe solid.
  
  Problems encountered area as follows:
  
  - Still able to pick up faces of the excluded solids when defining loads, restraints and contacts.
  - The software didn't recognise the thickened shell anyway and imported it as a solid.
  - It is very tedious defining the surfaces and thickening them in 2009.
  
  I'd estimate doing the exercise in 2008 took me less than a quarter of the time to do this in 2009.
  
  I have sent files (about 20 MB) to our VAR in Australia. I would be a relatively simple exercise to replicate if anyone is interested in giving it a try.
  
  Am I missing anything? Can anyone suggest an easier way.
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  - Vince Adams @ Derek Bishop on Oct 9, 2008 2:48 PM
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    Hi Derek,
    The only functional difference between the way you could choose the outer faces of a solid as the shell faces in 2008 and the way we do it in 2009 is that you indicate those faces in a Insert>Surface feature while in the modeling environment. Then you can either "Delete Body" the solid pipe or exclude it. Simulation will automatically recognize the surface as a shell body. It doesn't recognize shelled solids (an unfortunate coincidence of terms) as a shell body but will recognize sheet metal solids as shells.
    By indicating your shell faces with a surface, you have the opportunity to offset them to the midplane, where they should be, or leaving them on the outer faces of the solid where you had to place them in 2008. You don't ever need to thicken surfaces because of your Simulation modeling. One suggested workflow is to start in surfaces, which is appropriate for many large sheet metal weldments or plastic parts, and then thickening the surface after you know the design works. This is only an option to consider that has been effective in many cases, not a requirement.
    I have confirmed that you can select a face of an excluded component for loads and fixtures & have filed an SPR. Although this is a separate issue, I agree we should look into this.
    Can you break out a representative section of this and e-mail it to me or take some good screen shots? I'll be happy to do a quick video on how to address your challenge in 2009 and get that back to you.
    Thanks!
    
    -- Vince
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    - Derek Bishop @ Vince Adams on Oct 10, 2008 9:32 AM
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      Vince,
      
      I wasn't aware that you don't thicken the shells in the model. This explains why the model got picked up by Simulation as a solid as you noted. My oversight.
      
      I was able to improve the work flow by using a surface sweep along the pipe. This saves having to define a lot of annoying contacts. I imagine you could do the same in 2008. I would still have to create another part for this surface in 2008 and 2009. But granted, the surface at the mid plane is much better than on a boundary. I actually had to work off the inside surface of the pipe in 2008 due to the gaps between fittings which are greatest on the outside of the pipes.
      
      The main bug bear remains that I have to create another part in which to model the surface for the pipe. Not sure how much you know about routing. Each segment of the pipe is a different part in a subassembly which is built in a main assembly. Clearly it is a lot more work to apply a surface at the part level of each segment.
      
      Will try to attached is a screen shot of an analysis in 2009. I had to rebuild the model because the program kept crashing every time I opened the old one. Did I tell you I'm having trouble with 2009 crashing....
      
      If you still want the parts I can email them to you. Please confirm your email address.
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      - Vince Adams @ Derek Bishop on Oct 10, 2008 12:13 PM
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        Hi Derek, I certainly would like to look at the parts. If there is a hole in the logic when Routing is involved, we need to understand it.
        
        You can send parts to:
        
        Vince Adams
        18762 Chatham Way
        Lake Villa, IL 60046
        Tel:: 847-245-7099
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Simulation (Cosmos) 2009 and Shells

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