for a 3D model that is pressed against a table and electrified, how should the bottom surface be constrained?

In ABAQUS, for a 3D model that is pressed against a table and electrified, how should the bottom surface be constrained? I do not want to fully fix it, as I need to consider the material expansion due to temperature rise from electrical heating. When modeling, I do not include the table and apply constraints directly to the bottom surface of the module.