Preload dependent material properties of lamination stacks for electric machines

Abstract

AbstractThe design of electric machines is motivated by electromagnetic and mechanical requirements. The magnetic flux is confined and guided by ferrite cores which consist of coated electrical sheets with a thickness of only a few tenths of a millimeter in order to minimize the eddy current losses. This heterogeneous structure causes preload dependent transversal isotropic material properties which affect the fatigue behavior and structural dynamic behavior of the machine. The material constitutive equations are defined by five parameters which must be derived from experimental investigations with respect to compression in the stacking direction. In this paper, a test procedure is introduced to determine the elastic and torsional stiffness as well as the lateral elongation of the stack depending on its preload.