An Approach to Understanding Micro-Spalling in High-Speed Ball Bearings Using a Thermal Elastohydrodynamic Model

Abstract

High-speed main shaft ball bearings applied in new aircraft propulsion systems experience the most critical operating conditions ever in rolling bearing history. Rotational speeds, loads, temperatures, and demands on reliability have increased continuously over the last few years. The frequency of classical subsurface material fatigue in high-speed ball bearings is low due to designs with Hertzian stresses far below the fatigue stress limit. Corresponding to increasing speeds and temperatures, surface initiated fatigue became the most important failure mode of high-speed ball bearings. This article shows an approach to describe the phenomenon of micro-spalling in high-speed ball bearings supporting jet engine main shafts by using a thermal, Newtonian, fully flooded elastohydrodynamic model. The basic failure mode, kinematics, loads, and the results obtained within the contact zones of the ball bearing for various operating conditions are presented.