Two solids in contact with relative movement

Hi

I was wondering if there are any comments on the problem that I am working on it at the moment. Basically, consider two solid cylinders (like piston and cylinder) that the first one is moving inside the second one by time (transient analysis). The physics is all solid with no fluid interactions. The diameter of the inner cylinder (lets say piston) is bigger than the hole inside the outer cylinder. So when it enters the bigger cylinder, pressure will be inserted to both of the materials due to the contact between them and the geometries deform accordingly.

For the purpose of monitoring the change of the geometry by time, there is the need for a transient analysis to be applied here. And I assume that the moving mesh physics should be used in the boundary as well. However, I have problems in applying the moving mesh to the geometries as in the selection domain, all of geometries are "not applicable".

Is there the need to define any contact pairs for the two surfaces that will be in touch? Or any other details in the case? I have made a model of one quarter of the problem which you may find attached.

Thank you very much for your time to read and respond.
Sabah