A survey of the main aspects of magnetic forces and mechanical behaviour of ferromagnetic materials under magnetisation

The mechanical behaviour of ferromagnetic materials must be modelled for such complex problems as noises or vibrations of electric machines. The difficulties concerning that aim are defined. Then the various causes of Magnetostriction are presented. This paper focuses on magnetic forces. On this point, several theories are presented, and the most exciting are discussed, compared and developped. Indeed many doubts arise about the distribution of Magnetic force densitys, because diverse solutions are proposed and none appear certain. A synthesis is made between two of the most coherent approaches relying on energy methods. Then, formulations simple enough to be computed easily, are deduced. The proposed applications are detailed, providing the reader with corresponding volume force densities, associated stress tensors and surface forces densities, thus inviting practical verifications. As this paper limits itself to theory, only a few observations on this latter point will follow.