Simulation Mechanical and Multiphysics

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Valued Contributor
tfjield
Posts: 98
Registered: ‎06-19-2012

Weird Nodes

291 Views, 11 Replies
12-20-2012 02:44 PM

Hi Guys,

 

I'm performing a Transient Mass-Transfer simulation, and I noticed something strange.  Take a look at the following images:

 

Selection.png

 

The image on the left shows the results from the simulation.  The image on the right is the same part selected in the tree so that all the nodes are highlighted.  Say WHAT?!  Look at all those nodes that are outside of the physical part!

 

It's not just in the results environment.  Here's the same part in the FEA Editor:

 

Selection 2.png

 

I can even select those weird nodes:

 

Selection 3.png

 

Any idea what's going on here?  Is that a graphics artifact, or are my results being affected by these weird nodes?

 

NOTE:  This is one part in an assembly.  The rest of the parts are hidden...  Maybe it's showing nodes from those parts??

Current version of Mechanical & Multiphysics: 2013 SP2 (2013.02.00.0010 2-Oct-2012)
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Distinguished Contributor
ilyas
Posts: 141
Registered: ‎06-13-2012

Re: Weird Nodes

12-21-2012 01:51 AM in reply to: tfjield

Hi,

 

Can you select the elements(Selection tab>Select panel>elements)? If yes, then perhaps you can right-click>Inquire element information to find out which part it belongs to.

 

Regards

Ilyas

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Valued Contributor
tfjield
Posts: 98
Registered: ‎06-19-2012

Re: Weird Nodes

01-02-2013 10:25 AM in reply to: ilyas

ilyas wrote:

Hi,

 

Can you select the elements(Selection tab>Select panel>elements)? If yes, then perhaps you can right-click>Inquire element information to find out which part it belongs to.

 

Regards

Ilyas


Yes, I can select elements, and it says that the element is part of the part shown, even though it appears to be outside of the part itself.

Current version of Mechanical & Multiphysics: 2013 SP2 (2013.02.00.0010 2-Oct-2012)
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Valued Contributor
tfjield
Posts: 98
Registered: ‎06-19-2012

Re: Weird Nodes

01-02-2013 11:01 AM in reply to: tfjield

Here's an image.  Part 7 is the visible part.

 

Selection 4.png

Current version of Mechanical & Multiphysics: 2013 SP2 (2013.02.00.0010 2-Oct-2012)
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Distinguished Contributor
ilyas
Posts: 141
Registered: ‎06-13-2012

Re: Weird Nodes

01-02-2013 06:47 PM in reply to: tfjield

If it says that there is something there, then I would believe that something is there, and it might be affecting your results. What does Result Options>View>Element Visibility>Show All show you? Are the mysterious nodes overlapped by other parts?

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Valued Contributor
tfjield
Posts: 98
Registered: ‎06-19-2012

Re: Weird Nodes

01-03-2013 11:14 AM in reply to: ilyas

Yeah, from what I can tell, the mysterious nodes do overlap other parts...  But there are no results shading on them, as shown in the images above.  So it's kinda wierd...  If they were really there, why aren't they shaded?  Hmm.

Current version of Mechanical & Multiphysics: 2013 SP2 (2013.02.00.0010 2-Oct-2012)
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Valued Contributor
tfjield
Posts: 98
Registered: ‎06-19-2012

Re: Weird Nodes

01-14-2013 05:53 PM in reply to: tfjield

AstroJohnPE, do you have any ideas??  Is this just a graphical UI issue, or is it something more fundamental?

Current version of Mechanical & Multiphysics: 2013 SP2 (2013.02.00.0010 2-Oct-2012)
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*Expert Elite*
AstroJohnPE
Posts: 575
Registered: ‎08-30-2012

Re: Weird Nodes

01-15-2013 04:54 PM in reply to: tfjield

Because the nodes are shown in BOTH the Results and FEA Editor, I think the software believes there is a mesh there. By default, both environments do not "show" the lines/elements that are "inside" the part. My guess is that the internal mesh has somehow gotten outside of the physical part. Did you do anything unusual, such as creating or changing some of the mesh by hand? (In the FEA Editor, the internal mesh can be shown by "View > Visibility > Object Visibility > Internal Mesh". In the Results environment, "Results Options > View > Show Internal Mesh".)

 

If the problem were only in the Results environment, I have seen two cases (out of thousands) where the rectangle selection selects nodes in a different part of the model than where you drag the rectangle. But this is not the situation here.

 

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

Simulation Mechanical user since Dec 1997
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Valued Contributor
tfjield
Posts: 98
Registered: ‎06-19-2012

Re: Weird Nodes

01-15-2013 06:09 PM in reply to: AstroJohnPE

Yes, when I show the internal mesh, I can see all the extra stuff outside of the part both in the FEA Editor and in the Results environment.  Here it is in the FEA Editor:

 

Internal Mesh.png

 

No, I didn't do anything unusual...  I brought the part in from Solidworks and meshed it.  No manual operations.  I adjusted the mesh size on a few of the parts to ease the meshing process, but that's it.

Current version of Mechanical & Multiphysics: 2013 SP2 (2013.02.00.0010 2-Oct-2012)
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*Expert Elite*
AstroJohnPE
Posts: 575
Registered: ‎08-30-2012

Re: Weird Nodes

01-15-2013 06:53 PM in reply to: tfjield

I do not have any ideas how it happened, so I do not know if this will "fix" it or not. My suggestion is to copy the design scenario to a new one and mesh the model again. You do not need to run the analysis to see if it fixes it; either display the internal lines like you did, or do an "Analysis > Analysis > Check Model" to see what happens in the Results environment.

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

Simulation Mechanical user since Dec 1997
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