You can add a Phase subnode to nodes which define a load in order to prescribe the phase angle in a frequency domain analysis.

Together these define a harmonic load, for which the amplitude and phase shift can vary with the excitation frequency, f:

Add the phase load Fph for harmonic loads. Enter the phase for each component of the load in the corresponding fields.

Add the phase for the moment load Mph for harmonic loads. Enter the phase for each component of the moment load in the corresponding fields.

 Beam>Edge Load>Phase
 Beam>Point Load>Phase

Physics tab with Edge Load or Point Load selected:
Attributes>Phase