Improved Calculation of Dynamic Load Capacity for Cylindrical Roller Thrust Bearings: Numerical Update of the Lifetime Reduction Factor η for Bearings with Small and Medium Spin-to-Roll Ratios

Lubricants, vol. 13, pp. 65

Abstract

The standard procedures for calculating the lifetime of rolling bearings, defined by DIN ISO 281 and ISO/TS 16281, have been revisited in this work with a specific focus on redefining the η factor for cylindrical roller thrust bearings (CRTBs). The new η factor proposed in this study accounts for the additional spinning motion of the rolling elements on the raceway, which affects the lifetime of thrust roller bearings. By considering different spin-to-roll ratios (SRRs), the revised η factor results in a smaller lifetime reduction, improving from a 42% reduction with η = 0.85 to a 27% reduction with η = 0.91. This modification opens industrial opportunities for bearings that can handle higher loads or feature fewer or smaller rolling elements while maintaining the same lifespan target as bearings sized with the original η factor. An analytical and numerical methodology was developed to calculate the η factor for various bearing configurations. Two bearing geometries were selected to assess the influence of the SRR on bearing life. The methodology integrates calculations of the total friction coefficient, 2D and 3D stress distributions, and lifetime predictions based on subsurface-initiated fatigue failure modes. The numerical results demonstrate the impact of contact stresses and bearing kinematics on η. Although this study was based on numerical simulations, it sets the groundwork for experimental validation. Future work includes experimental testing to validate these findings, with a focus on subscale CRTBs subjected to varying γ values. Accelerated testing strategies, including higher rotational speeds and optimized lubrication, are proposed to enhance the accuracy of the results. These experiments would provide further insights into the life expectancy differences between various configurations, contributing to more precise lifetime calculations for CRTBs.

Authors 4

1. Paul Sauvage
   Affiliation as printed

   Independent Researcher, 75000 Paris, France

2. Torben Terwey

   ThyssenKrupp (Germany)

   Affiliation as printed

   Thyssenkrupp Rothe Erde Germany GmbH, Beckumer Str. 87, 59555 Lippstadt, Germany

3. Benjamin Lehmann Aachen MSE – Institute for Machine Elements and Systems Engineering

   RWTH Aachen University

   Affiliation as printed

   MSE—Institute for Machine Elements and Systems Engineering, Schinkelstraße 10, 52062 Aachen, Germany

4. Georg Jacobs Aachen MSE – Institute for Machine Elements and Systems Engineering

   RWTH Aachen University

   Affiliation as printed

   MSE—Institute for Machine Elements and Systems Engineering, Schinkelstraße 10, 52062 Aachen, Germany