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CBUSH element

Solution Partner Pioneer Solution Partner Pioneer
Solution Partner Pioneer

hi all,

 

i am just doing modal analysis of an electronic box. in that i have connect the diskdrives by using CBUSH element. after connecting CBUSH element i am getting error message 316,350 and 9002.

please help me how to use CBUSH element and how to connect it betweeen two solids.

i have attached the model.please go through...

 

 

regards,

shreeharsha

14 REPLIES

Re: CBUSH element

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Hello!,

Simply read the NX Nastran output file *.f06 and search for word FATAL, you will have there the reason of the error: you have defined CBUSH element no. 450 where the same node is used twice to orient the element.

 *** USER FATAL MESSAGE 350 (IFS350)
     THE FOLLOWING GRID OR SCALAR POINTS ARE SPECIFIED MORE THAN ONCE ON THE BULK DATA ENTRY SHOWN BELOW:
        408
 *** USER FATAL MESSAGE 316 (IFPDRV)
     ILLEGAL DATA ON BULK DATA ENTRY CBUSH   
     User information:
     See Bulk Data entry description in Section 5 of the NX NASTRAN
     Quick Reference Guide. If you are using the large field format make
     sure the number of entries is even.
 CBUSH        450       8     366     408     408                                

Editing the element 450 we see the reason of the error:

cbush-error.jpg

 

Simply instead the third-node use the option CSYS = Basic Rectangular, and you are done!.

Best regards,
Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: CBUSH element

Solution Partner Pioneer Solution Partner Pioneer
Solution Partner Pioneer

thank you sir.

it works well...

Re: CBUSH element

Creator
Creator

Hi,

 

I have a similar problem with TETA element. One element is using one of nodes twice. What would you advise to do with it ?

 

Best regards,

Weronika

Re: CBUSH element

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear Weronika,

Well, you have a problem, CTETRA is a 3-D solid model then not possible to "repeat" a node, the solid element will be planar, then NX NASTRAN will complaint giving error. The solution?, simply remesh your part and make sure the mesh quality is good, use TOOLS > CHECK > ELEMENT QUALITY to check that all elements pass the NX NASTRAN quality control.

Best regards,
Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: CBUSH element

Creator
Creator

Thanks for your answer, Blas

 

That's right, elements like that become 'flat'. Untortunately, I've tried remeshing with smaller element size and I kept getting the same error.

In one case I got a different errors like: 

USER FATAL MESSAGE 350 (IFS350)

USER FATAL MESSAGE 316 (IFPDRV)

 

which says almost the same - that one node is used twice in one CTETRA element.

 

My last idea is simplifying the geometry. Do you think it might help ?

 

All the best,

Weronika

Re: CBUSH element

Creator
Creator

Sorry, I meant 

 

USER FATAL MESSAGE 4654 (ETETGD)

 

not 350 & 316

Re: CBUSH element

Genius
Genius

Post here your model, usualy femap mesher dont create elements with repeated nodes, maybe the error is somewhere else.

Re: CBUSH element

Creator
Creator

I enclose the FEMAP neutral file in v11.2. 

This is a part of a larger drum, so some surfaces are divided due to connections to other parts. 

 

Weronika

Re: CBUSH element

Genius
Genius

Actualy mesher produce bad mesh at default mesh setting.

Spoiler
Element Quality
   Quality Check               Number Failed      Worst Value
      Aspect Ratio                     848           36652.77
      Taper                              0                 0.
      Alternate Taper                    0                 0.
      Internal Angles                 4461           119.2943
      Skew                            4270        0.000423228
      Warping                            0                 0.
      Nastran Warping                    0                 0.
      Tet Collapse                    1987           1631644.
      Jacobian                        2445           1.000006
      Combined Quality                4482                 1.
 
   4482 Elements Failed out of 4535 Checked.

Some elements have aspect ratio more than 35000 - it is unacceptable for solver. You can carefuly manualy set mesh size on each curve to get good mesh or use tool Mesh->Revolve->Element (before this step you must slice you ring and create plate mesh on cross section of ring) and revolve plates into hexa elements.

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