Virtual Forces (Eddy Current)

Virtual force in an eddy-current problem is computed the same way as virtual force in a magnetostatic problem. The only difference is that the average value of force over time is computed — not the instantaneous force at a given time.

The difference between the time-averaged (or DC) force, AC force, and instantaneous force is shown below:

Force oscillates at twice the frequency of the source current and magnetic field:

where

• f_F is the frequency of the force.
• f_S is the frequency of the source current and magnetic field.
• T_F is the period of the force.

The time-averaged (or DC) force, AC force, and instantaneous force can be determined by

The AC force, F_AC must be evaluated at a particular phase (=wt) in order to determine its magnitude at an instant in time. However, the peak value of the AC force is reported as the “AC Magnitude” in the force and torque solution panel for Maxwell 2D.