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In this paper, a new calculation method of relative fatigue life considering surface texture on high-speed and heavy-load ball bearing is presented. Rolling bearing quasi-dynamics, micro-TEHL analysis, non-Gaussian surface simulating technique and stress analysis with FEM are combined to obtain the relative fatigue life. The maximum subsurface stress with the new method are compared with data in inference, the relative error is 3.9%, which caused by decreasing surface stress under high speed. The non-Gaussian surface textures effect on surface pressure and shear stress are studied, which show transverse texture perpendicular to entrainment direction is helpful to form film because of the increasing hydrodynamic effect, and decrease the pressure and shear stress, but longitudinal texture has an opposite effect. Non-Gaussian parameters effects on relative fatigue life are researched, which display relative fatigue life increase with the increase of transverse texture, and decrease with the increasing longitudinal texture. The increasing skewness and curtosis can bring the decrease of relative fatigue life, but the relative fatigue life is beneficial as skewness is negative and curtosis is small, which is helpful for bearing life. Finally, the whole relative fatigue life of inner race and balls are given. [ABSTRACT FROM AUTHOR]

The timing gears of the ship internal combustion engine usually undergo dynamic loading conditions, and often work in a mixed lubrication state. In this study, by considering the three-dimensional (3D) machined roughness, an integrated model with the analysis of mixed lubrication state and dynamic-meshing performance for the spur gear is developed. The model is verified by comparing its results with the predictions using the typical line-contact EHL formulas. The machined roughness apparently affects the local 3D distributions of the film pressure and thickness. The shaved surfaces have the minimum film thickness ratio and the worst lubrication state, while the polished surfaces can improve the lubrication performance of the timing gear pairs greatly. Under the conditions of heavy-load and low-speed, almost all of the Hertzian contact zone appears to be in contact with 0 film thickness, and the local maximum pressure may lead to serious stress concentration, film breakdown, and excessive wear, etc. By optimizing the gear module and pressure angle, the loading capacity of the timing gear is promoted and the contact area gets reduced, the lubrication state improves significantly from mixed lubrication to full film lubrication. • An integrated model with the mixed lubrication and dynamic-meshing performance for the spur gear is developed. • The mixed lubrication model of the timing gear pairs with 3D real roughness is built. • The effects of machined process on mixed lubrication state of the timing gears have been researched. • The ways to improve lubrication by optimizing the gear modulus and pressure angle are investigated. [ABSTRACT FROM AUTHOR]

The damage evolution induced by three types of carbides in M50 bearing steel is studied in this paper. Stress distribution in the micro-domain is initially obtained to calculate the damage accumulation of the elements. Subsequently, the process of the butterfly generation is simulated. It can be seen that the butterfly wings are generated at the sites where maximum stress appears. The irregular shape carbide seems to be most harmful to the bearing material. Finally, the effect of residual stress on damage evolution induced by the carbides is investigated. The result shows that higher temperature, smaller balls and ion implantation are beneficial for the strengthening of residual stress and hence damage accumulation rate is reduced. [ABSTRACT FROM AUTHOR]

This paper focuses on the crack nucleation and crack propagation induced by a cluster of carbides. The morphology of the carbides is extracted from scanning electron microscope images of M50 bearing steel. Subsequently, a continuum damage accumulation model is incorporated into the Voronoi finite element model to investigate the damage evolution in the material. It can be observed that nearly all the micro-cracks nucleate on the boundary of the carbide and propagate through the bearing material matrix around those carbides until they become large enough to coalesce to failure. With the increasing of friction coefficient, cracks gradually grow to the contact surface. The result also shows that the carbides deeper than a certain depth are not harmful to the material. [ABSTRACT FROM AUTHOR]