Modeling the effects of torsional stress on hysteretic magnetization

Opposite torques applied axially to a polycrystalline ferromagnetic rod res ult in tensile and compressive stresses acting perpendicularly at the rod s urface at 45 degrees to the rod asis, These stresses affect the magnetizati on of the rod when a magnetic field is applied parallel to the rod asis. it is shown hom one can formulate the magnetomechanical hysteresis model so a s to treat this special case of biaxial stress and take into account the ef fect of opposite torques on the magnetic properties of the rod. Variation o f hysteresis parameters such as coercive field, remanent Bus density, diffe rential permeability at the coercive held, and hysteresis loss as a functio n of applied torque are determined from the model. In the model, the torque is applied first and then the field is cycled to give hysteresis loops. It is found that the torque dependence of the magnetic properties is differen t, depending on what is chosen for H-max, the maximum value of the applied magnetic field H. The best parameter to use for tracking the torque is foun d to be H-c at saturation or near saturation, since that parameter shows an almost linear decrease with the applied torque.