Abstract: Electromagnetic forces of ferromagnetic materials consist of
attractive and repulsive components, which can be introduced from the Lorentz
force formula and the Kelvin force formula. In harmonic fields, the attractive
and the repulsive forces both have DC and AC components and they cancel out
with each other to reduce the total average force. The contributions or
influences of the frequency, magnetic permeability and electric conductivity of
the material to attractive and repulsive forces in time-varying fields are
analyzed and simulated by the numerical experiments using FEM methods. Results
show that the total time average electromagnetic forces can be reduced greatly,
even to zero in certain states, which is useful to control the vibration
problem.
