Finite element analysis of electrical machine vibrations caused by Lorentz, Maxwell and magnetostriction forces

In order to numerically predict the stator vibration spectrum, the mechanical behaviour of the stator (for low modal density) is correlated with the force distribution inside the machine. This force distribution is found considering the coupling between the magnetic and the mechanical finite element systems. This coupling results in a finite element based force expression covering both Lorentz forces and Maxwell forces. Using a weak coupling approach, magnetostriction forces are added to the force distribution. The numerically predicted stator vibration spectrum of a synchronous machine is compared to stator surface measurements