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Joining 1D meshes together

Hi everybody!

 

I am working in NX 9 with a 1D model made of 3 sketches. I mesh each one separately with the option "merge nodes" enabled and apply the tubular section (each mesh one different radius). Some lines of the sketches touch each other, so on the final display the meshes cross each other at some points. After the applying loads and fix constraints, when solving, the solver does not create the results. I though it may be a problem of degrees of freedom or similar. I have seen that in the simulation there are some "glueing" tools but i do not know how to apply them to the 1D element. 

How can I merge the meshes to make the three meshes deform as one solid body?

 

Thanks in advance Smiley Happy

 

Cheers, Bernardo

4 REPLIES

Re: Joining 1D meshes together

Dear Bernardo,

It is very easy, use command DUPLICATE NODES, select all the meshes you want to check and you will see higlighted the coincident nodes. Simply click on MERGE NODES 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: Joining 1D meshes together

Thank you Blas for the answer!

 

But I still have the problems when solving. I apply a normal load on one mesh point and fix another one and, after solving,  when I click in results it appear: "No results are found"

What do you think it may be the problem?

 

Cheers, Smiley Happy

 

Bernardo

Re: Joining 1D meshes together

Dear Bernardo,

Take a look to the *.F06 file located in the dimulation directory, open with any TEXT editor and there you will see the reason of the error.

Also, to detect rigid body motions in your FE model, simply run a eigenvalue SOL103 analysis, if you have unmerged nodes then you will be able to animated deformed shape of rigid motions with 0.0 Hz.

Finally, if you are not successful to detect the error post your ZIPed model here to see what happens really.

Best rergards,

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: Joining 1D meshes together

Dear Blas, 

 

I Just saw this topic online and I have exactly the same problem. I now which node of the structure is the problem, but when I  dont want to fix the DOF of the tube where it says it is "free". Even when I fix the node, where it says it is not fixed, it does not work. 

 

Below the ERROR Summary:

SUBCASE 1
0
GRID POINT ID DEGREE OF FREEDOM MATRIX/FACTOR DIAGONAL RATIO MATRIX DIAGONAL

1040181 T2 8.29470E+15 1.23602E+08
1040181 R2 -1.47346E+16 6.14774E+09
^^^ USER FATAL MESSAGE 9137 (SEKRRS)
^^^ RUN TERMINATED DUE TO EXCESSIVE PIVOT RATIOS IN MATRIX KLL.
^^^ USER ACTION: CONSTRAIN MECHANISMS WITH SPCI OR SUPORTI ENTRIES OR SPECIFY PARAM,BAILOUT,-1 TO
^^^ CONTINUE THE RUN WITH MECHANISMS.
*** USER INFORMATION MESSAGE 4110 (OUTPBN2)
END-OF-DATA SIMULATION ON FORTRAN UNIT 12
(MAXIMUM SIZE OF FORTRAN RECORDS WRITTEN = 1 WORDS.)
(NUMBER OF FORTRAN RECORDS WRITTEN = 1 RECORDS.)
(TOTAL DATA WRITTEN FOR EOF MARKER = 1 WORDS.)
1 JUNE 14, 2017 NX NASTRAN 1/ 6/15 PAGE 19

 

The tube connections look like this: 

1D_Mesh_Problems.JPG
Sometimes it is only the top node, sometimes it are all three nodes you can see in the picture. The tubes are drawn as 1D connections. 

 

Any ideas?

 

Kind regards, 

 

Chris

 

(This is my first post, so if something is not as it is expected on here, let me know!)