Asymetric Cylinder Boundary Conditions

[beh188]

Hi,

I am working in ANSYS Workbench and modeling a ring about 2" thick, 6" diameter, with a 0.25" width keyway cut through it. There are also 2 holes drilled through the ring at about a 100 degree angle to eachother. I would like to apply a pressure normal to the inner surface of the ring and observe the stress. However, I am having trouble setting up the boundary conditions. Applying the pressure results in a net force causing rigid body movement (this is due to the keyway intersecting the inner ring surface and no pressure is applied to it). In real life, the inner surface of the ring will be pressed onto a shaft. I have attempted to model the inner surface as a compression only support in hopes of the inner surface serving as a contact support to counteract the rigid body movement. However, the compression only contact does not appear to be applied to the solution (perhaps because the inner ring surface is an incomplete cylinder due to the keyway splitting it.

Any thought on how to constrain the model?