NX 7.5 surface-to-surface contact

[TimEv]

Hello,

I'm setting up a simulation in 'Advanced Simulations' with NX 7.5. Thereby I need to use the 'simulation object' Surface-to-surface Contact. In this command, I select 2 faces and fill in a friction coefficient.

If I solve the solution, NX Nastran solves the simulation, but when I want to view the results, an error pops up and tells me the results are in a wrong format.

When I use the command in NX 6 in exactly the same way, I don't have the problem. Do I need to activate some parameters in NX 7.5 to solve the problem or is there something else wrong?

mvg,
Tim Everaert

 

[BlasMolero]

Hello!,
This is the typical behaviour of NX AdvSim when you have error in the solution: not any error appear in the screen. But if you revise your nx nastran output file *.f06 you will see there the reason of the error, look for word "fatal".

Without the model in hand is dificult to estimate the reason of the error, but as you mention to perform a "surface-to-surface" contact, please check you don't have in your model rigid body motions. Also, increase the amount of RAM memory devotd for the analysis, say minimum 1024mb.

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48011 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

 

[TimEv]

Hello,

thank you for replying!

I also tried the 'surface-to-surface contact' on a small, simple model. There I applied a 'fixed constraint' on all parts, so there are no rigid body motions.
Even with this simple model I'm getting the same message. If I delete the 'surface-to-surface contact' and replace it by an 'mesh mating condition', the simulation solves and I get to see the solution.

I also searched the '.f06'-file and I couldn't find any 'fatal' error.

mvg,
Tim Everaert

 

[BlasMolero]

Dear Tim,
NX7.5 AdvSim comes with new NX Nastran 7.0 where the number of iterations to get contact convergence is set to 20 iters. In previous versions if the convergence was not achieved, the solver accepted the obtained values, but in NX Nastran 7.0 the solver stops solution progress and do not save results, this could be ONE reason of the error ....

Then, all that happens in your model is saved in the *.F06 file (prtname_simx-solutionname.f06), of you open the file and read with patient line by line you will see definitely the reason of the error.
Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48011 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

 

[ThomasTheTrain]

Turn off the iterative solver option.
I fought with this for a few days. When your mesh contains more than 80% 3D elements, NX recommends turining on the iterative solver, so I did. It took 2 days before I realized this was causing all my solutions with surface to surface contacts to fail.
Don't understand it, just know that everything is running smooth and all I did was turn off the iterative solver option.

Iterative Solver Option = Edit Solution -> General Tab - > Iterative Solver