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Statics - only simple support constraints

Experimenter
Experimenter

Hello All ,

Is it possible to define only simple support constraints in the model ? (in ex. thin plate simple supported on edges ) .

Or I have to define at least 1 fixed constraint to get the results ?

 

Thank you !!!

7 REPLIES

Re: Statics - only simple support constraints

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear Alex,

I don't understand very well the question, could you please make a drawing sketching the problem?.

You can define any constraint you like (pinned or fixed), in geometry or directly in nodes, but your model should be stable, not rigid body motion should exist or the NX NASTRAN solver will give you FATAL error, OK?.

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: Statics - only simple support constraints

Experimenter
Experimenter

Hi Blas, thank you for replying .

When I trying to define only simple support constraints (4 edges) for my model (some box lid) I get the message "No results are found" if I tying to open the results . It seems that the solver didn't solve the solution because the solve time too short  (even for 101 linear).

In case that I add a fix constraint - everything going OK and I get reasonable results .

But than I have some unwanted stress results in the areas where the fix constraints were defined.

Re: Statics - only simple support constraints

Legend
Legend

Yep, that is pretty normal...  If you really need to have only the simple support, then you can look at inertia relief...

Re: Statics - only simple support constraints

Experimenter
Experimenter

Hi TENTECHLLC ,

Does it means that I will get same "bug" if I'll run the 106 Nonlinear ?

 

Re: Statics - only simple support constraints

Legend
Legend

It's not a bug, it's the nature of the analysis, the solver wouldn't know what to do with the unrestrained dof... 

Re: Statics - only simple support constraints

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear Alex,

Please revise your nx nastran *.f06 output file in the model directory and search for FATAL word, you will see there the reason of the error.

Or better run a Normal Modes/Eigenvalue analysis (SOL103) and animate the first mode shape, you will see the reason of the error, why your model is wrong constrained (to learn more take a look to my post at the following address: https://iberisa.wordpress.com/2011/02/20/mensaje-de-error-de-nx-nastran-run-terminated-due-to-excess...

Or post your full NX AdvSim model here --both *.prt, *.fem & *.sim files-- and we will take a look to it, OK?.

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: Statics - only simple support constraints

Experimenter
Experimenter
Thank you Blas and TENTECHLLC ,
For now I solved it by defining small enforced displacement in reasonable areas .