Iron Losses, Magnetoelasticity and Magnetostriction in Ferromagnetic Steel Laminations

The interdependence of iron losses and magnetoelasticity in ferromagnetic laminations is studied by numerical simulations. For the simulations, a finite-element model for the eddy currents in the lamination is coupled to a constitutive magnetomechanical material law. We demonstrate how the experimentally apparent rate-dependency of magnetostriction partly results from the comparison of the local surface magnetostriction to the average flux density supplied through the sheet. The average flux density is a global quantity and lags behind the local surface magnetostriction due to the skin effect of the eddy currents. Accurate modeling of the skin effect also shows that in addition to the hysteresis losses, the eddy-current losses also change as a result of applied mechanical stress, contrary to some earlier discussions in the literature.