Modeling effects of varying torsion in magnetized steel

In this paper, we develop a model for magnetization changes in a steel rod under varying torsion in a constant applied magnetic field. At any point on the surface of the rod under torsion, the magnetization changes, in a small region about the point, are driven by biaxial stress changes, which are equal in magnitude, with one stress change tensile and the other compressive, and with the stresses acting at ±45 degrees with respect to the rod axis, tangentially to the surface of the rod. In this paper, we demonstrate how to extend the “law of approach” of and the energy balance equation to irreversible magnetization changes under varying torsional stress at constant magnetic held. As an illustration of how the model is used, a prediction is made showing changes in axial flux density at the surface of the rod when the torsion is cycled five times between zero and a maximum value of torque