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Contact Convergence

Experimenter
Experimenter

Hello,

 

I'm having trouble getting my outer loop contact convergence to converge.  The inner force loop converges early on like the 15th iteration but the outerloop never does.  Does anyone have any ideads of what I could check or try to fix to help the model converge?

5 REPLIES

Re: Contact Convergence

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Hello!,

I don't understand what means "outer loop/inner loop contact", please explain.

 

If you have problems with contact convergence, check the definition of your SOURCE & TARGET regions, this is the main issue: check that mesh in both source & target regions is the most possible matching each other, this is critical, having matching meshes helps a lot to easy convergence.

 

Also check your mesh density, in contact regions the mesh should be refined, not coarse, and matching as much as possible.

 

Please note that almost all is explained & written in the NX NASTRAN manuals, read them with attention: the following picture tells you do not use ONLY ONE region for the whole model, is preferible to define many connectors with many regions if the geometry is changing sharply, OK?.

 

Also, check that every region has perfect mesh continuity, do not define islands inside regions, this maks the region inactive.

 

contact-recommendations.png

 

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: Contact Convergence

Experimenter
Experimenter

Thank you, I was able to get my model to converge after improving my mesh quality.  I have seen the part of the Nastran manual referenced and have attempted to keep my mesh sizing as consistent as possible.  I also had checked the normals for plate elements and expanded elements on regions to make sure all the elements I expected were shown.  I have attached some info that explains outer and inner loops a bit.

 

Thanks again,

 

Albert

Re: Contact Convergence

Experimenter
Experimenter
Hi stressed1234

I want to ask you where I can find femap manual tutorial for new version. I seeked on web but unsuccessfully. I sow your attachements and see 2 pictures about tutorial.
Thanks in advance
Mechanical Engineer Dragoljub Ilic

Re: Contact Convergence

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom
Hello!,
The FEMAP manuals are installed in your hard disc during installation as well as the NX NASTRAN manuals. Simply go to HELP > HELP TOPICS for FEMAP HELP, or HELP > NX NASTRAN for NX NASTRAN Help, or HELP > EXAMPLESS for example problems.
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: Contact Convergence

Creator
Creator

Blas,

 

So here is a question for you - you wrote on my other thread where I was getting a problem with a mesh mating condition such that the nodes are appearing both on the master and slave of the contact pairs.

 

Per your reply above, how do I do both - create the mesh mating condition AND avoid having the node be both on the master and slave of the contact pair?

 

(I'm using a surface-to-surface contact condition now, so it is no longer glued. I used the glued condition because I needed to simplify the model so that I can debug other possible causes of convergence issues before I have solve everything else, so now all that is left is just this surface-to-surface contact condition.)

 

Thanks.