Rotordynamic effects of bearing misalignment and arrangement in angular contact ball bearing with full stiffness matrix

Rotor-bearing modeling is essential for the safe operation of rotating machinery. Typically, in practice, bearings can be loosely fitted to the housing to allow axial thermal elongation of the rotor which can cause misalignment of the bearing. This phenomenon is investigated in this study using a full ball bearing stiffness matrix including cross-coupling terms with a three-dimensional solid finite element rotor model. The effect of misalignment on bearing stiffness and rotordynamics is studied. The results show a significant drop in stiffness due to drastic changes in the contact forces and their distribution between the balls and the raceway. Consequently, there are changes in the rotor’s critical speeds and mode shapes as a result of bearing arrangement and misalignment.