Rolling Bearing Stress Based Life—Part I: Calculation Model

Abstract

Rolling contact bearing life is calculated using stresses calculated at the surface and in the volume. Surface stresses account for profile and misalignment as well as asperity deformations. Sub-surface stresses are calculated beneath the asperities (for defining the life of the surface) and deeper in the volume for calculating the life of the volume. The stress-life criterion adopted is the Dang Van one in which the local stabilized shear stress is compared to the material endurance limit defined as a function of the hydrostatic pressure (itself a function of the contact pressure) but also residual stresses and hoop stresses (due to fit). A stress-life exponent c, of the order of 4 (instead of 34/3 in the standard Lundberg and Palmgren model) is used for respecting a local load-life exponent of 10/3 at typical load levels. Life of any circumferential slices of the inner, outer, and roller is defined for obtaining the final bearing life. Trends showing how the bearing life varies as a function of the applied bearing load and Λ ratio (film thickness/RMS roughness height) are given.