Hi Bill thank you very much. Unfortunately the command does not seem to create periodic boundary conditions (here is an example of what I want to do: Theory of Periodic Boundary Condition implementation in FEM - YouTube)
"I discovered that the Mechanical GUI would not allow me to apply forces to periodic boundaries, which is why I instead used a command object to define periodicity as a workaround".
How did you originally enforce the periodic boundary conditions before you used the workaround? As far as I can tell other researches only applied the loads to the corner nodes (as shown for example in the video), which is maybe why the GUI did not allow you to apply forces to PBC.
I am looking forward to your answer.