Shell Surface-to-Surface (non-glue) Contact Issues
Shell Surface-to-Surface (non-glue) Contact Issues
(OP)
Greetings,
Short version:
I am somehow messing up sheet/shell surface-to-surface contact (not glued)
Long version:
I am currently using NX Nastran 7.0 and dealing with shell contacts. I made a simple model of 2 shell sheets, .5" shell thickness value, stacked on top of eachother (space between sheets is .5"). I did a simple compression run (sheets in the XY plane, vertical 'up' is +Z) with a small force in the -Z direction. The only way I can get it to run is with glued contacts.
The error I get in the F06 file when using non-glued contact is:
USER FATAL MESSAGE 9143 (SUPER3)
THE SOLUTION FOR THE RESIDUAL STRUCTURE DOES NOT EXIST.
The exact model with glued contact runs fine and gives good results. The only parameter I am setting manually is AUTOSPC=1, everything else is straight default.
I have tried constraining the top shell sheet in to travel only in the Z direction, but this did not help.
A run with 1 sheet and 1 solid works fine with surface-to-surface, non-glue contact.
I knew I was in trouble when I didnt find anything here about the subject (longtime lurker).
Any help on the method or settings I am goofing up would be appreciated.
Thanks,
Dan
Short version:
I am somehow messing up sheet/shell surface-to-surface contact (not glued)
Long version:
I am currently using NX Nastran 7.0 and dealing with shell contacts. I made a simple model of 2 shell sheets, .5" shell thickness value, stacked on top of eachother (space between sheets is .5"). I did a simple compression run (sheets in the XY plane, vertical 'up' is +Z) with a small force in the -Z direction. The only way I can get it to run is with glued contacts.
The error I get in the F06 file when using non-glued contact is:
USER FATAL MESSAGE 9143 (SUPER3)
THE SOLUTION FOR THE RESIDUAL STRUCTURE DOES NOT EXIST.
The exact model with glued contact runs fine and gives good results. The only parameter I am setting manually is AUTOSPC=1, everything else is straight default.
I have tried constraining the top shell sheet in to travel only in the Z direction, but this did not help.
A run with 1 sheet and 1 solid works fine with surface-to-surface, non-glue contact.
I knew I was in trouble when I didnt find anything here about the subject (longtime lurker).
Any help on the method or settings I am goofing up would be appreciated.
Thanks,
Dan





RE: Shell Surface-to-Surface (non-glue) Contact Issues
You could try a static and/or buckling (eigen value) solution determine if you have rigid body motion.
Brian
www.espcomposites.com
RE: Shell Surface-to-Surface (non-glue) Contact Issues
Did you defined the Global Contact Parameters in the BCTPARM / Case Control Tab? If not you have to define those parameters as the number of iterations, initial penetration etc... You might also try to reverse contact directions bu changing between the source and the target. NX is surprisingly good when it comes to NOT WORKING and output-ing ERROR messages.
There is a little movie in the NX HELP where it is shown an example of making a simple contact, surface to surface between a shaft and a wheel. You can look for it and do the exact same steps and the same settings...It worked for me..sometimes...other times i did the exact same steps and i get a error message. I delete every thing and start from scratch..and it works...
Hope this helps
RE: Shell Surface-to-Surface (non-glue) Contact Issues
Thanks to all that read and all that responded. I apologize for the long question from a silly mistake.
RE: Shell Surface-to-Surface (non-glue) Contact Issues
I still cant get it to cooperate for the automatic pairing contacts...
Thanks again everyone!
RE: Shell Surface-to-Surface (non-glue) Contact Issues
Things to check when defining maually "surface-to-surface" contacts with SHELLS:
• Contact distance definition in the contact property should entered correctly: in this case use 0.5 or bigger, say 0.51 is correct.
• Surface orientation: Shells elements have TOP/BOT faces, then SOURCE & TARGET regions should point at each other, if not contact will not be success.
• By default, shell offset is on, then NX NASTRAN accounst for Shell thickness in the contact interations.
• INIPENE parameter accounts for initial penetration: this is the most important parameter to define correctly in surface-to-surface contact, by default is defined as "CALCULATED", this means that if NX NASTRAN solver find any penetration between source/target contact elements then will resolve the "interference-fit" situation, and you will see locally high stress, then mind your steps, OK?.
With GLUE surface-to-surface contact, the orientation of shell elements is not critical.
Best regards,
Blas.
~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director
IBERISA
48011 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog de FEMAP & NX Nastran: http://iberisa.wordpress.com/
RE: Shell Surface-to-Surface (non-glue) Contact Issues
Great tips. Thank you very much!
Dan