Hello, you can of course model the cylinder as an axisymmetrical (2D) task.
If you for some reason need a full 3D calculation, I am afraid in the current version, you can only define a pressure load perpendicular to a surface using the local coordinate system in the "Load Force for Surface" condition, but not easily prescribe such a displacement. However, if you tell us more about the problem setup, we might be able to suggest some other way of modelling it?

In the worst case, you have to define a simple distinct displacement load on the surfaces (e.g., 1m in X and 2m in Y), and edit it in the .inp file to introduce the correct functions for the dependence of the load on the position (coordinates).

The comon way to model corrosion expasion is to simply apply expansion to the whole steel crossection, see, e.g., the article Peter KOTEÅ , Miroslav BRODŇAN / University of Žilina, Civil Engineering Faculty, Department of Structures and Bridges in our 2/2009 newsletter http://www.cervenka.cz/newsletters/news … 09-october
You do not need to prescribe the volume change through temperature, you can directly apply the condition Initial Strain for 2DElem Surface.

If you think a uniform expansion of the whole steel cross section (i.e., a diameter increase) is not good enough in your case, please explain why and we try to help you find a way of modelling.

Dear Teresa, I am not sure if I understand your question - when the X and Y strains are identical, it means a uniform expansion. For a uniform expansion, the values are the same in any coordinate system (and therefore, it does not matter if using the global or some local CS).