Is there a way to assign different contact types to different vertices lying on the same surface? The surface contact or shrink fit option for some reason never works correctly, so I thought I could partially bond two parts, which are normally supposed to be in surface contact with friction, so that I can show the structural behavior that I want to show and at the same time can avoid surface contact problems. This is actually something that I previously did completely casually (http://forums.autodesk.com/t5/Autodesk-Simulation-
Contact can only be defined between two surfaces, two parts, or a combination of one part and one surface. So your options are to split the surface in your CAD application (better choice), or change the surface numbers of the lines once you are in Simulation Mechanical. If you change the lines in Mechanical, be aware that those lines that you changed may still exist when you remesh the model. (I do not remember all of the details about what "user created" lines are kept on remeshing.)
If you have not provided an archive of your model ("File > Archive > Create") which demonstrates the problem you are having with surface contact and shrink fit, that would be another alternative.
16.9 years experience with Simulation Mechanical