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Imported NASTRAN model has a few enormous elements

Good Morning All,

I'm a newbie who is will eventually try a flutter analysis.

But I can't get by the first step of importing my NASTRAN model from another software: a few of the elements and constraints are enormous. I can neither delete the nodes nor zoom in anough to delete the elements. I looked through the discussions here, to no avail. 

 

Do you have any suggestions? (The model is ok in the other software.) Thanks.

 

NX NASTRAN error.jpg

5 REPLIES

Re: Imported NASTRAN model has a few enormous elements

How did you import the mesh?  Was it a Nastran deck or some direct translation?

 

In any case, did you compare the coordinates of the nodes on the elements to the data in the import file you used to import the analysis?

Best Regards,
Chip Fricke
Principal Applications Engineer - Femap Product Development

Re: Imported NASTRAN model has a few enormous elements

I imported the .nas file. It doesn't have any meshes - it's all rods, beams, rigids, and panels. The .nas file in the other software gives a correctly sized model.

 

I guess I'll have to figure out how to look at the .modfem data deck with a text editor?

 

Thanks.

 

Re: Imported NASTRAN model has a few enormous elements

Can you please send me the .nas file to chip.fricke@siemens.com?  Append a .txt file extension to it.

Best Regards,
Chip Fricke
Principal Applications Engineer - Femap Product Development
Solution
Solution
Accepted by topic author flyboy2160
‎12-15-2016 12:00 PM

Re: Imported NASTRAN model has a few enormous elements

Thanks for sending the .nas deck.  I found an multiple GRID (node) entries as follows that causes the nodes to go out to space.    This is not a Femap error - it's simply reading what's in the input deck.

 

GRID*   2409            0               0.              100000000000000.*A8781  
*A8781  0.                                                                      
GRID*   2410            0               0.              0.              *A8782  
*A8782  100000000000000.                                                        
GRID*   2411            0               100000000000000.0.              *A8783  
*A8783  0.                                                                      
GRID*   2412            0               0.              -1.+14          *A8784  
*A8784  0.                                                                      
GRID*   2413            0               0.              0.              *A8785  
*A8785  -1.+14                                                                  
GRID*   2414            0               -1.+14          0.              *A8786  
*A8786  0.

Best Regards,
Chip Fricke
Principal Applications Engineer - Femap Product Development
Solution
Solution
Accepted by topic author flyboy2160
‎01-18-2017 12:07 PM

Re: Imported NASTRAN model has a few enormous elements

I ended up changing those enormous data entries back to 100s. The frequency model ran fine with them at those smaller values, but would not run if those points/fake elements were deleted.