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Static Analysis. MultiSet. Gap as Contact. Error.

Valued Contributor
Valued Contributor

Hello.
Beam scheme contains elements of Gap . Calculation of NX Nastran Static Analysis with the option "Gap as Contact"
If you carry out the calculation MultiSet
Boundary Conditions:
Constraints 1  Load 1
Constraints 1  Load 2
Constraints 1  Load 3
Constraints 1  Load 4
then the Load 3, we have the error 9137 (GRID POINT ID 530 R1 MATRIX / FACTOR DIAGONAL RATIO -3.62356e + 15)

 

If we draw a separate calculation :
Constraints 1 Load 3
That error is not, why ?

5 REPLIES

Re: Static Analysis. MultiSet. Gap as Contact. Error.

Phenom
Phenom
Did you create a new analysis set, or edit the multi-set analysis set when analysing the single condition?
If you used a new set, please confirm that you also set Gaps as Contact for the 2nd analysis to be certain they are still working as contact rather than just springs.

Re: Static Analysis. MultiSet. Gap as Contact. Error.

Valued Contributor
Valued Contributor

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Re: Static Analysis. MultiSet. Gap as Contact. Error.

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear Cfytrr,

I suggest to revise your *.F06 file to see if contact solution is converged, the maximum number of contact iterations by default is 20, then you need to check if the message NUMBER OF OUTER LOOP ITERATIONS EXCEEDED appear in the *.F06 file.

If this is the case, this means that the last  contact iteration is reached without convergence.  Hence, the deformed shape is not the right one expected. Top workaround this issue, one can set  a connection property so that a BCTPARM card  can be written in your nastran deck file.

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: Static Analysis. MultiSet. Gap as Contact. Error.

Valued Contributor
Valued Contributor
Blas Molero.

How to change the parameter BCTPARM for  Gap elements ?
In my model lacks Connection property ( for contacts between the surfaces and bodies ) is the only Beam and Gap elements .

Re: Static Analysis. MultiSet. Gap as Contact. Error.

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Hello!,

You can edit the NX Nastran deck and enter the BCTPARM card values, for instance:

 

BCTPARM      108    PENN     10.    PENT      1.    MAXF      20        +       
+           MAXS      40    CTOL    0.01    NCHG    0.02    MPER        +       
+         REFINE       0

The BCTPARM card above comes from  “Define Connection Property” dialog box setup in FEMAP.

I mainly change Max Force Iterations (MAXF) and Max Status Iteration (MAXS); and penalty Factor like Normal Factor (PENN)  and Tangential Factor (PENT). The others are the default ones  (see BCTPARM card description in the QUICK REFERENCE GUIDE manual). You can set them manually if you want.

 

But the question is: was your contact solution converged?.

When you rerun your model no specific warning or error should appear. So always it is very important to check *.f06 file after a run for potential issues. 

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/