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In order to improve the starved lubrication condition of rolling bearings, three kinds of textures, namely dimple, groove texture, and gradient groove texture, were developed on the guiding surface of thrust ball bearings in this study. The results show that gradient groove texture has the one-way self-driving function of liquid droplets. The root mean square (RMS) value of vibration acceleration of gradient groove textured bearing (GGB) decreased by 49.1% and the kurtosis decreased by 24.6% compared with non-textured bearing (NB) due to the directional spreading effect of gradient groove textures on oil. The frequency domain analysis showed that the textures mainly suppressed the medium and high-frequency energy of bearing vibration, and the GGB was reduced the most with 65.3% and 48%, respectively. In addition, whether the grease is sufficiently sheared has a large impact on the oil guiding effect, and the friction torque of GGB could decrease by 10.5% compared with NB in the sufficiently sheared condition. Therefore, the gradient groove texture with oil self-driven effect on the guiding surface of rolling bearing can effectively improve the lubrication condition of the bearing and thus reduce the bearing vibration and friction torque, which has a promising application prospect. [ABSTRACT FROM AUTHOR]

Considering the radial clearance, roller crown profile and discontinuous contact between the roller and cage, a nonlinear dynamic model for skidding behavior of the cylindrical roller bearing is established based upon the Hertz contact theory and elastohydrodynamic lubrication. Through comparisons with both reference and experimental results, the proposed model is verified. Various load conditions are considered for their effects on single roller’s skidding behavior. It is shown that local skids exist and periodically vary with the roller revolution, especially for the roller entering and leaving the load region. Increasing the values of radial load, bending moment or amplitude of time-variable load all reduces the maximum roller slipping velocity, which means that the roller skids are attenuated. After considering the time-variable radial load, the frequency of time-varying slipping velocity is not the orbital speed but the combination of the inner race frequency and orbital speed. [ABSTRACT FROM AUTHOR]

For the rolling element bearing–rotor system, the bearing stiffness and eventual system vibration performance are influenced by the shape and position errors of the bearing housing. In this article, a rotor supported by two cylindrical roller bearings is investigated. The load and deformation between the roller and the raceways of the bearing and the bending deformation of the rotor are analysed. An analytical model is established for calculating the radial and angular stiffnesses of the bearing considering the bearing housing deflections. Consequently, a vibration model which can consider the influences of the bearing housing deflections is developed for the bearing–rotor system. With a calculation example, the influences of the housing deflection angles on the vibration performance of the bearing–rotor system are studied numerically and a series of conclusions are obtained and explained. [ABSTRACT FROM PUBLISHER]

Grease plays an important role in reducing friction and wear of rolling bearings and improving their service life and reliability. However, increasing attention is being paid to the environmental pollution caused by discarded grease. In this paper, calcium sulfonate complex grease (CSCG) was prepared by using green raw materials, namely poly-alpha-olefin oil as the base oil and complex calcium sulfonate soap as thickener. In order to improve the lubrication and damping performance of the grease, hexagonal boron nitride (hBN) and nano-Al 2 O 3 , which have the potential to replace toxic additives, are mixed into the grease in different mass proportions. The thickener structure of each grease was characterized and analyzed. According to the bearing vibration and life of the two key performance indicators, four-ball tests and bearing vibration tests under limited lubricant supply (LLS) were performed. The results show that CSCG with 0.75 wt% hBN and 0.25 wt% Al 2 O 3 (BN75AL25) has the best tribological and vibration suppression performance. The mean friction coefficient decreased by 11.3%, the wear scar diameter decreased by 6.1%, and the worn surface morphology improved significantly compared with CSCG. The frequency domain analysis showed that high, medium and low frequency vibrations were suppressed by 19%, 11.7% and 16.4%, respectively. In conclusion, BN75AL25 has the potential to become a green high-performance grease under LLS, which is worth further research and exploration. [Display omitted] • The nano-hBN can promote the formation of calcium carbonate protective layer. • The nano-Al 2 O 3 can improve the tribological performance of the grease with hBN. • The nano-hBN and nano-Al 2 O 3 can reduce the vibration by momentum exchange. [ABSTRACT FROM AUTHOR]

This paper presents a comparative study of the tribological and vibration performance of the synthesized lithium complex grease (LCG) containing Carbon black, Fe 3 O 4 and Al 2 O 3 nanoparticles on rolling bearing. The micromorphology, friction coefficient, worn surface and bearing vibration experiment of four greases were studied. The results show that in presence of nanoparticles friction and wear behaviors are improved compared to LCG without nanoparticles. The best tribological performance is obtained in presence of Al 2 O 3 nanoparticle, which is mainly attributed to its high hardness, cylindrical shape and deposition on the worn surface. Further, the wettability test shows that Al 2 O 3 nanoparticles can effectively promote the flow of base oil on the LCG soap fibers, which results in the most effective bearing vibration suppression. • The Al 2 O 3 nano-particles have the largest hardness and show cylindrical microscopic morphology. • The Al 2 O 3 nano-particles were intensively deposited on the surface of worn steel ball. • The Al 2 O 3 nanoparticles effectively promote the flow of base oil on the LCG soap fibers. [ABSTRACT FROM AUTHOR]

To evaluate the effects of CuO nanoparticles on friction and vibration behaviors of grease on rolling bearing, lithium complex grease (LCG), polyurea grease (PG), calcium sulfonate complex grease (CSCG) and these three greases containing 1 wt% CuO nanoparticles were prepared respectively. The microstructure, friction coefficient, wear surface and bearing vibration test of six greases were investigated in detail. The results show tribological properties of PG are improved most significantly, with the friction coefficient and wear scar diameter decrease, and the wear surface is fine and smooth. This is mainly attributed to the synergistic effect of lamellar thickener structure and CuO nanoparticles. Further, the addition of CuO nanoparticles to PG also has an obvious inhibitory effect on bearing vibration. • The three thickeners show coiled fibrous, lamellar and reticular microstructure. • The CuO nanoparticles have different effects on friction of the three greases. • The CuO nanoparticles affect the vibration of bearing with three greases. [ABSTRACT FROM AUTHOR]