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Press Fit Contact analysis with thermal load, finite friction and large deformation (CREO4)

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Press Fit Contact analysis with thermal load, finite friction and large deformation (CREO4)

I'm experiencing insanely long run times (36+ hours) when trying to run this analysis.  When I change the contacts to infinite friction it runs in about 1.5 hours.  My hunch is that there's a simple check-box I'm missing or there is some other simple reason this is happening.  I need to use finite friction to get realistic results but I can't wait 2 days per run.  Any ideas?

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5 REPLIES 5

Re: Press Fit Contact analysis with thermal load, finite friction and large deformation (CREO4)

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Re: Press Fit Contact analysis with thermal load, finite friction and large deformation (CREO4)

Thanks.  But the problem I'm having is that I'm getting very different stress results from a colleague using Nastran.  I'm trying to dial CREO in to get similar results.  In other words, I don't trust the results.  In the CREO 4 case, my stress results are much lower than expected. 

Re: Press Fit Contact analysis with thermal load, finite friction and large deformation (CREO4)

unfortunately i don't have creo4

Re: Press Fit Contact analysis with thermal load, finite friction and large deformation (CREO4)

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Re: Press Fit Contact analysis with thermal load, finite friction and large deformation (CREO4)

Hello

 

Unfortunately I´m still using Creo 2.0 that gives only two frictions option (no friction / infinite). I work a lot with contact, including LDA contacts and contact with hyperelastic materials.

 

Sometimes the simple fact of choosing finite / infinite friction lead to a huge changing is solving time – or even to non-convergence at all. I always have a bad feeling about running LDA with contact or hyperelastic materials with contact because it takes a lot of time and it is not clear if the simulation will finish or not. However I have cross-checked Creo results with others FEM and usually the results (stress, forces, etc.) have a good agreement.

 

So for your case please keep in mind that the finite friction option implemented since Creo 3.0 was known to have nasty problems/bugs – I´m not sure how they are now with the last version of Creo 4.0.

 

My suggestion is to break down your simulation in steps to compare results with Nastran (with the same constrains). Also play a bit with the mesh near the contacts. Aditionally I see a lot of features in your CAD that may not be relevant in your simulation. Cleaning the model and using symmetry is another good way to reduce computation time.

 

Make the 1st simulation exploring the interference only (press fit) and compare it with Nastran. Play with different frictions modes and compare them with Nastran. This may show you a possible bug in Creo 4.0. Create a contact volume region with better mesh if you are interested in good stress results – otherwise the automatic mesh (coarse) can provide a quicker job and even converging the simulation – when a fine mesh fails. My experience showed that what is a good mesh for "no friction" does not works for "infinite".

 

The final step once you are sure about the setup and the results is would be to apply the thermal load and compare the results.

 

Good luck!

 

Ps: If you have assembled the CAD parts with interference make sure that the interference gap in Creo is large enough to capture this initial state.