The frequency dependence of the loss per cycle in ferromagnetic sheet material

The energy loss per cycle has been measured as function of frequency from 0 to 80 Hz in low-carbon lamination steel. Under sine flux excitation, the loss per cycle is linear with frequency, as predicted by simple models but unlike measured results on oriented silicon-iron. Numerical calculations based on a modification of the Pry and Bean model show that if the domain size is sufficiently small relative to the sheet thickness the loss per cycle vs frequency plot will be linear even if the domain wall spacing decreases with frequency.