I am generating a 2D plane stress model where I am having problems when defining the contact pairs between the teeth of the rack and pinion.
I would like to generate 2 sets with just the elements of the teeth surfaces and select these sets for the contact pair.
However, I am not able to select any set when defining the contact pairs, that is why I did “Search contact pairs” and selected the one that takes into account all the elements in both parts.
When runned I get this error:
I am not sure if I gave all the neccessary information, so that you can help me. Apparently, new users cannot upload files. SO i would be greatful if you can tell me which additional information you need me to send…
Contact is based on surfaces (groups of element faces), not whole element sets. Surfaces in 2D are defined on edges. You can define them manually or use the Search contact pairs feature but with a proper tolerance and making sure that only external surfaces that may come into contact are selected instead of whole parts.
Selecting surfaces (edges in 2D) for contact directly:
Thanks for the explanations!
However, I tried during all the day but was not able to find the error.
Perhaps could I ask you to send me an example of the 2d gear pair that you have in the figures above (.inp). I could compare the .inp file with my own and try to find the error in the definition.
Thank you very much!
May I have any problem in my computer or am I doing something wrong? I just completed the model, applying a torque in the pinion and rotation in gear… What can I check?
Thanks!!
Input file importer is quite outdated compared with exporter and you may have to redefine some things after importing. Here, you would need to redefine the surfaces. From this:
Even if the inporter is outdated compared with the exporter, I imagine that if the input file is properly written and the file is runned from the cmd it should work, right?
Because my final aim is to learnhow PrePomax writes .inp files to make my own and be able to run then directly from the cmd.
Thank you!
Also, replying to what you tols me about surface redifining. Instead of selecting the surfaces of the set in the contact pair , I selected the edges manually so now I have it as you told me.
The error i get is the same as I had before.
Those incorrectly defined (due to .inp file import) surfaces with N instead of element face label are the problem. Even if you define new (correct) surfaces for contact, you have to delete the incorrect ones.
So you can do this to make it work:
Import my .inp file to 2D plane stress model.
Delete those 2 surfaces and 2 user keywords (imported as such due to the aforementioned importer limitations, they can be deleted in the Keyword Editor).
Add Surface Behavior to Surface_Interaction-1.
Define new contact pair like you already did.
Create new Analysis and run. Then there will be no errors.
Of course, you will also need some proper loads and BCs since my test inp doesn’t have them.
When you say Keyword editor, what do you mean?
Do you mean editing .inp file in program such us Notepad or do you mean another thing?
Once I import the .inp file if these not proper surfaces appear, I will always have the problem, isn’t it?
You can’t delete them this way. Surfaces need to he deleted directly from the model tree (Mesh —> Surfaces container). Keyword editor only allows you to edit keywords that were added using it and 2 of the keywords from the imported input file are recognized as such (because they aren’t fully supported by the importer). So delete the surfaces normally (from the tree) and the 2 contacf keywords highlighted in purple using the keyword editor.
