Finite element analysis of a soft mounted 2-pole asynchronous machine concerning vibration stability

The paper describes a finite element calculation concerning vibration stability of a 2-pole asynchronous machine with sleeve bearings and flexible shaft, mounted on soft foundation elements. The finite element model considers the rotor, stator, end shields and bearing housings, oil film stiffness and damping, the electromagnetic interaction between rotor and stator - deduced from an electromagnetic field calculation -, the gyroscopic effect of the rotor and the influence of the foundation stiffness and damping. The critical mode shapes and natural frequencies are calculated for different rotor speeds and the eigenvalues are analyzed to receive the limit of stability. Therefore the paper shows a calculation method to optimize the vibration stability by considering foundation stiffness and damping.