Modeling of a high-speed rolling bearing and its damage mechanism analysis

Rolling bearings are widely used in high-speed rotating machinery systems, such as, aero-engine rotors, high-speed CNC machine tool spindles and high-speed locomotive wheelsets. The mechanical properties and running states of bearings affect the accuracy, reliability, and life of the whole rotor system significantly. When a rotor-bearing system is rotating at high speed, the generated centrifugal forces and gyroscopic moments raise the loads on the bearings, meanwhile, the bearing inner rings expand radially due to the centrifugal force. In addition, with increase in the running time, the working temperature rises and thermal deformations appear in the rotor, bearings and other parts. Due to the combined effects of the centrifugal force and the rising working temperature, the geometric position relations of the parts inside bearings change, they lead to the change of bearing properties, such as, stiffness, stress and strain. Here, considering the effects of radial centrifugal expansion and thermal deformations on the geometric displacements in bearings, Jones's bearing model was improved and a mechanical model for a high-speed rolling bearing was proposed, it was used to predict contact angles, contact deformations and contact loads between rolling elements and bearing rings. The bearing stiffness was calculated with it as well. Based on the proposed mechanical model, the laws of contact loads and contact position in a bearing were investigated under different working conditions, i.e., static loads, dynamic loads and high speeds. Afterwards, the damage mechanism and incipient damage locations of a bearing were analyzed on the basis of the fatigue failure theory of materials. The study results provided a theoretical reference for damage detection and fault diagnosis of a high-speed rolling bearing.