Investigation of non-uniform preload effect on stiffness behavior of angular contact ball bearings

Preloading is an effective way to maintain good performance of angular contact ball bearings. Traditionally, the rigid and constant preload are applied by uniform approaches on the bearing system. However, non-uniform loads occur while the surfaces of spacer are obliquitous at rigid preload or the stiffnesses of springs are inconsistent at constant preload. In this article, a new approach is proposed to incorporate the non-uniformity effect. Using this approach, the bearing performance under practical operating conditions could be improved. At first, the critical relationship between the stiffness behavior and the non-uniform preload of the ball bearing system is studied. Then, based on Jones' model, the stiffness function of angular contact ball bearings with non-uniform preload is established analytically. Based on the functions, boundary conditions are determined and used to calculate the local contact deformation and predict the bearing stiffness when the preload is non-uniform. Finally, the stiffness of both ceramic and steel ball bearings under non-uniform preload and various operating conditions is simulated. Comparing with traditional methods, the new method has better performance in stiffness prediction under non-uniform preload. It will give a designer a deep insight on the dynamic analysis and optimization of the rotor-bearing system.