simulation of electrode

[proEdj]

I am currently using coupled field elements to model a beam made of PZT. Using a force input on the beam (opposite of the fixed end) I have seen non-zero voltages at all the nodes. Now, I would like to simulate the presence of electrodes on both the upper and lower surface of the beam. I want there to be no mechanical presence of the electrodes, just free flowing of electric charge across the referenced surfaces.

What is a good way to simulate this? I attempted to modify my boundary conditions and define constant voltage on the surface nodes, but this vaule is not constant with respect to time. At any given time the voltage should be constant across the surface, but the magnitude changes with time. I do not see how to apply this in ansys.

Thanks