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Simulation of a cross country ski

Hi

I use NX9 advanced simulation and want to simulate a corss country ski to touch the ground.

I modeled a ski with curved surfaces and a block as ground. At first I did a SOL 101 Linear Statics - Global Constraints calculation. And defined a surface to surface contact between the ski and the block (ground), on the top of the ski is a pressure (simulate the person on the ski) and the block is fixed constrained on the bottom. 

 

The Problem now is the ski is not moving to until the block(ground) see (picutres) but the ski transfer stress to block without touching it.

 

Now I start to do a SOL 106 Nonlinear Statics - Global Constrains calculation, but there I can't choose a surface to surface contact. And I wrote that in this calculation the programm know when a body is penetrating a other body. But in my solution the ski penetrate the block(ground) and do not transfer any stress.

 

If you have any idea how I constrain the ski without a block, I'm really thankful.

 

Sorry for my english

 

Thank you

5 REPLIES

Re: Simulation of a cross country ski

It sounds like you have the problem set up correctly in SOL 101. Any time you do a contact analysis, particularly when there are initial gaps in the model, you always need to post process deformations at a 1::1 scale. Anything else and the relative motion between components may not look correct.

 

SOL 106 does not support surface-surface contact. The advanced nonlinear solution (SOL 601, 106) does.

Re: Simulation of a cross country ski

Hi,

thank you for your answer.

I tried to run it with advanced nonlinear solution SOL 601. But it is not running, if I want to open the resulte it display me "The file solution.op2 is not fund.".

 

In the F06 - Datei it show me:

 

Checked in NX Nastran license feature nx_nas_advnlin_dsk.
*** END SOL 601 ***
*** FATAL ERROR: SOL 601 DID NOT FINISH SUCCESSFULLY.
*** ADVANCED NONLINEAR EXIT CODE 0 ***
*** ISHELL PROGRAM 'NXNA' COMPLETED ***
^^^ USER FATAL MESSAGE
^^^ ERROR IN ADVANCED NONLINEAR MODULE 0
^^^SOL601 FAILED

 

Are there any spacial adjustments what I have to do.

I also can't find any examples in the internet for SOL 601.

 

Thank you

Re: Simulation of a cross country ski

I find also in the F06 - Datei:

 


OUT OF BALANCE LOADS LARGER THAN INCREMENTAL LOADS AFTER ITERATION 7



*** STOP BECAUSE OUT-OF-BALANCE LOADS LARGER THAN
INCREMENTAL LOADS ***
*** ERROR NO. A1802 ***

No convergence,out-of-balance load too large,automatic time stepping might help

 

 

What is that mening?

Re: Simulation of a cross country ski

In SOL 101, contact is formed prior to the solution, so contact stiffness will stabilize any bodies with rigid body motion. You can constrain the base and apply the full load to the top of your ski and the solution will work.

 

In SOL 601, contact penetration is checked during the solution after loads are applied. In a load controlled solution, you need to apply very small incremental loads in the first time steps to allow contact to be established. If you apply the full load to a model like this, the rigid body motions will be too large for the contact to establish itself properly.

Re: Simulation of a cross country ski

Thank you for your Answer!

 

Right now I working on a SOL 601 and it make sense to me that I have to start with very small incremental loads in the first time steps.

 

I searched for some guidlines and videos to get into this problem, but I can't find something. Can you give me a hint/tip how to handle it?

 

Where can I find the time steps? (I read in the F06 - Datei that my simulation is just using one time step)

 

Best regards