A dynamic model of a three-point contact ball bearing-rotor system: numerical and experimental verification

Three-point contact ball bearings (TPCBBs) belong to the main bearings of aeroengines. Their contact state will change significantly with external forces, which will affect the nonlinear vibration responses of rotor systems. This paper presents a quasi-static model for a 5-DOF TPCBB, taking into account various external conditions. Using the structure of a certain aeroengine as a reference, both the TPCBB’s quasi-static model and a cylindrical roller bearing model are introduced into the dynamic model of the TPCBB-rotor system. An innovative solving method, which combines the Newton–Raphson method and the Newmark-HHT method, is proposed. The solving method is used to analyze the acceleration responses, displacement responses, and contact forces of the TPCBB-rotor system with varying axial and radial forces. Furthermore, the validity of the proposed model is verified by a comparison of simulation and experimental results. The results indicate that the three-point contact state and the two-point contact state of the TPCBB will switch with the change of axial and radial forces. Compared with the three-point contact state, the acceleration amplitude and displacement amplitude of the system in the two-point contact state are smaller. And the contact forces between the balls and one of the inner rings will become 0 N.