Inventor General Discussion

Inventor General Discussion

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Registered: ‎12-30-2013
Post 1 of 3

Meshing Problem (Model Extremely thin)

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01-07-2014 09:02 AM

Hi everyone,

 

I'm facing with mesh problem in which it state that the model are very thin as shown in figure below...

 

mesh.JPG

 

hope i can get some ideas to solve it....

 

Thanks.

 

Valued Mentor
313 Posts
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Registered: ‎10-06-2011
Post 2 of 3

Re: Meshing Problem (Model Extremely thin)

01-07-2014 09:16 AM in reply to: ridzal90

Do a quick search of "Find Thin Bodies" and read what causes this error.  Here is a response from a AD employee who specializes in Inventor Simulaton....

"Hi Dan,

  This is a warning message that is basically saying that the surface area to volume ratio is relatively high for these bodies, and they might be better solved using shell elements.

  If those components are the same ones we looked at earlier this week (square hollow tubing) it may be interesting to use a shell idealization rather than solid elements.  But unless they are very, very long I think solid elements are fine for the analysis.

  However, if you get this message for say very long I-beam geometry, there could be fillets that would cause gaps (missing faces) in the midsurface due to non-uniform wall thickness if the I-beam.  Connectors (bonded contacts to 'bridge' gaps or missing face) are needed to connect the disjoint shell bodies in the midsurface.  In these types of geometry it would be preferable to use solid elements, since the idealized thin model could be too different from reality.  There is also Frame Analysis as a different option, so that beam elements can be used for the long structural memebers.

  In summary,shell elements are best suited for very thin-walled bodies, such as large sheet metal parts or pressure vessel tanks, etc.  One of the main reasons is that (for instance thin plates) you need several layers thick of solid elements in order to not make the meshed model 'too stiff' in bending, and the large number of solid elements needed could make the problem size huge.  With shell elements, this 'too stiff because of not enough layers of elments' is not an issue.  But be aware that with a shell element formulation, we assume a linear stress distribution through the thickness using our DKT shell elements.

Hope this helps! -Hugh"

GSE Consultants Inc.
Windsor, ON. Canada
Distinguished Contributor
138 Posts
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Registered: ‎10-21-2011
Post 3 of 3

Re: Meshing Problem (Model Extremely thin)

01-07-2014 04:26 PM in reply to: GSE_Dan_A

I think Dan explained it perfectly, if you can, post the part so we can understand the example better and discuss which meshing aproach might be better.

 

RM

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