Study on nonlinear stiffness of rolling ball bearing under varied operating conditions

Nonlinear stiffness of rolling bearing is the root cause of the nonlinearity of a bearing rotor system. In this paper, bearing stiffness is calculated with a complete model for angular contact ball bearing. The bearing stiffness matrix is then integrated with finite element model of a rotor to study the nonlinear stiffness of rolling bearings. Calculated results are compared with the results of FAG´s online tool (BearinX®) and experiments as well. The good agreements show the accuracy of the presented model. Based on the model of a two-bearing rotor system, the variations of bearing stiffness are studied from three aspects, i.e., external axial forces effects, external radial forces effects, and high speed effects, which may provide theoretical proofs for the study of bearing rotor systems.