Stiffness characteristics of angular contact ball bearing considering thermal - mechanical coupling

Abstract

When the rotor is rotating at high speed, the ball bearing stiffness exhibits strong nonlinear characteristics. This paper primarily investigates the influence of different speeds, axial loads, and other factors on the angular contact ball bearing stiffness. To address the inconvenience of simultaneously simulating dynamic temperature fields and deformation results using ANSYS software, a novel coupling method is proposed to achieve simulation results that closely resemble actual working conditions. By utilizing a MATLAB script program based on Palmgren's friction heat generation theory, real-time extraction of frictional heat generation in high-speed angular contact ball bearings under combined shaft action, radial load, and speed is achieved. The obtained heat generation results are then applied as boundary conditions in the finite element model of bearings to establish a coupling field for further analysis. Subsequently, Ansys Workbench simulates the impact of this coupling model on relative displacement between inner and outer rings under identical load and speed conditions to ultimately obtain dynamic stiffness results for angular contact ball bearings. A novel approach to calculating stiffness was introduced in the subsequent bearing stiffness test bench, wherein the radial load and relative displacement of the measured angular contact ball bearing were determined by converting material mechanics formulas. This method effectively addresses the inconvenience of measuring bearing stiffness in rotor systems and aligns with simulation results.The findings indicate that bearing dynamic stiffness increases with axial load at constant speed, with axial stiffness being greater than radial stiffness. Additionally, higher rotational speeds under coaxial loads result in more pronounced increases in frictional heat but lead to decreased overall stiffness. The feasibility of simulation results from thermal-mechanical coupling models has been demonstrated.