Magnetic forces and magnetostriction in rotating electrical machines

The deformation of magnetic origin in ferromagnetic cores is due to both magnetic forces and magnetostricion. The deformation of closed magnetic circuits, such as transformers, is commonly analysed by considering magnetostriction only, while in systems with an airgap, such as rotating electrical machines, only magnetic forces are considered for the analysis of vibrations and noise of magnetic origin. Nevertheless, both phenomena, magnetic forces and magnetostriction are present in both types of magnetic cores. In this paper, both magnetic forces and magnetostriction and their resulting stresses and strains in rotating electrical machines are illustrated by means of finite element computations.