Effects of External Stress on Magnetic Properties in Motor Cores

Abstract

Effects of fixing by shrink fitting on magnetic properties of iron coros are investigated to simulate magnetic behaviors of iron cores fixed in motor flames. Shrink fittings, of course, decrease their permeabilities and increase effective magnetostrictions and magnetic losses. It is well known that the magnetostriction increment and the permeability decrement are explained with the increase of magnetoelastic energy due to compressive stress by shrink fitting. The magnetic loss increases, however, cannot be explained with this energy. We show experimentally that the magnetic loss increases are occurred from the mechanical work due to the magnetostrictive movement of iron core under the compressive force.