Relaxation methods applied to the problem of a.c. magnetization of ferromagnetic laminae

The distribution of the magnetizing force inside a ferromagnetic lamination subjected to a.c. magnetization at its surface is determined by the application of Southwell´s relaxation methods, on the assumption that the static (or d.c.) characteristics of the material are applicable directly at any point in the lamination under dynamic (or a.c.) conditions. The flux and eddy-current distributions and the ¿dynamic hysteresis loop¿ are then evaluated. The alternative conditions of sinusoidal magnetizing force (at the surface) and sinusoidal total flux are considered for a frequency of 50 c/s. Consideration is also given to higher frequencies of operation when the surface magnetizing force is of sinusoidal waveform.