Vibrations of rigid rotor systems with misalignment on squirrel cage supports

Based on the structural features of a rigid rotor on squirrel cages elastic supports, a finite element (FE) model of the system including squirrel cages is adopted to study its vibration and stress characteristics under the case of bearing misalignment. Firstly, the equations of motion are derived through Lagrange method to obtain the basic dynamic characteristics. Then a three dimensional FE model is established and validated after model updating on basis of the calculated and measured modes and imbalance response. Finally, the influences of bearing misalignment on the rigid rotor system on elastic supports are studied. Results reveal that, for the rigid rotor on elastic squirrel cages supports, bearing misalignment has no obvious influence on the transverse vibration of shaft. However, the stress level on squirrel cage increases significantly, which means the easier damage of bearing and squirrel cage when the bearing misalignment appears.