Film Thickness, Friction, and Scuffing Failure of Rib/Roller End Contacts in Cylindrical Roller Bearings

1992 ◽  
Vol 114 (2) ◽  
pp. 311-316 ◽  
Author(s):  
H. Aramaki ◽  
H. S. Cheng ◽  
D. Zhu
Keyword(s):  
Film Thickness ◽  
Critical Load ◽  
Strongly Correlated ◽  
Wear Process ◽  
Load Dependence ◽  
Roller Bearings ◽  
High Speeds ◽  
Lubrication Performance ◽  
Minimum Film Thickness ◽  
Cylindrical Roller

The lubrication performance of rib/roller end contacts of cylindrical roller bearings was studied both theoretically and experimentally for end-crowned rollers and inclined ribs. A partial EHL program was used to calculate the film thickness and the friction in the rib/roller end contact. Calculated minimum film thickness shows a strong load dependence although the central film thickness is still a weak function of the load. The influence of the contact position on the film thickness was also investigated for roller skewness and design tolerance. It was found that the contact location affects the minimum film thickness strongly in spite of a weak influence on the central film thickness. Friction and scuffing experiments were conducted on a special rig, which can achieve arbitrary slide/roll ratio to simulate the rib/roller end contacts. Good agreements were found between measured and calculated friction based on the assumption that the lubricant was Newtonian. In scuffing experiments, scuffing propagation was observed on the rib contact surface. The critical load for scuffing is strongly correlated with the sliding velocity. The critical load at high speeds is lower than that at low speeds although the friction at high speeds is lower. These data imply the importance of the contact location and the wear process for film breakdown.

Study on curved surface design of sliding pair based on stepped topography model

2019 ◽  
Vol 72 (1) ◽  
pp. 86-92 ◽  
Author(s):  
Zhenpeng Wu ◽  
Vanliem Nguyen ◽  
Zhihong Zhang ◽  
Liangcai Zeng
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Liquid Film ◽  
Bearing Capacity ◽  
Fluid Film ◽  
Curved Surface ◽  
Surface Model ◽  
Content Type ◽  
Lubrication Performance ◽  
Minimum Film Thickness

Purpose The stepped topography of the friction pairs mainly causes the fluid film thickness to change in the direction of motion. In this region, there have very few topographical design methods for continuous or non-linear distribution of the fluid film. The purpose of this study is to analyze the effect of the curved surface on the performance of the liquid film. Design/methodology/approach First, a numerical simulation is used to solve the optimal bearing capacity and friction coefficient of the liquid film under the condition of the minimum film thickness. Then, the curved surface described by the sinusoidal curve equation is applied in the transitional region of maximum and minimum film thickness. The bearing capacity and the friction coefficient of the liquid film are respectively simulated and compared in the same condition of the minimum film thickness. Findings The research results show that the liquid film using the curved surface transition model, the optimal bearing capacity is significantly increased by 32 per cent while the optimal friction coefficient is clearly reduced by 38 per cent in comparison with using stepped surface model. Originality/value The friction pair with curved transition enables better lubrication performance of the liquid film and better adaptability under unstable conditions.

scholarly journals Elastohydrodynamic Film Thickness Model for Heavily Loaded Contacts

1974 ◽  
Vol 96 (3) ◽  
pp. 472-479 ◽  
Author(s):  
S. H. Loewenthal ◽  
R. J. Parker ◽  
E. V. Zaretsky
Keyword(s):  
Film Thickness ◽  
Measured Data ◽  
Type Ii ◽  
X Ray ◽  
Polyphenyl Ether ◽  
Load Dependence ◽  
Test Conditions ◽  
Wide Range ◽  
Minimum Film Thickness ◽  
Thickness Measurements

An empirical elastohydrodynamic (EHD) film thickness formula for predicting the minimum film thickness occurring within heavily loaded contacts (maximum Hertz stresses above 1.04 × 109 N/m2 (150,000 psi)) was developed. The formula was based upon X-ray film thickness measurements made with synthetic paraffinic, fluorocarbon, Type II ester and polyphenyl ether fluids covering a wide range of test conditions. Comparisons were made between predictions from an isothermal EHD theory and the test data. The deduced relationship was found to adequately reflect the high-load dependence exhibited by the measured data. The effects of contact geometry, material and lubricant properties on the form of the empirical model are also discussed.

scholarly journals Effect of Geometry on Hydrodynamic Film Thickness

1979 ◽  
Vol 101 (2) ◽  
pp. 231-237 ◽  
Author(s):  
D. E. Brewe ◽  
B. J. Hamrock ◽  
C. M. Taylor
Keyword(s):  
Film Thickness ◽  
Boundary Conditions ◽  
Classical Solution ◽  
Exact Expression ◽  
Geometry Effect ◽  
Load Dependence ◽  
Viscosity Effects ◽  
Minimum Film Thickness ◽  
Contour Plots

The influence of geometry on the isothermal hydrodynamic film separating two rigid solids was investigated. Pressure-viscosity effects were not considered. The minimum film thickness is derived for fully flooded conjunctions by using the Reynolds boundary conditions. It was found that the minimum film thickness had the same speed, viscosity, and load dependence as Kapitza’s classical solution. However, the incorporation of Reynolds boundary conditions resulted in an additional geometry effect. Solutions using the parabolic film approximation are compared with those using the exact expression for the film in the analysis. Contour plots are shown that indicate in detail the pressure developed between the solids.

Thermal Elastohydrodynamic Lubrication of Axially Crowned Rollers

2021 ◽  
pp. 1-21
Author(s):  
Wassim Habchi
Keyword(s):  
Film Thickness ◽  
Design Parameter ◽  
Numerical Study ◽  
Elastohydrodynamic Lubrication ◽  
Negative Influence ◽  
Reference Case ◽  
Critical Design ◽  
Lubrication Performance ◽  
Minimum Film Thickness ◽  
Line Contacts

Abstract This work presents a comprehensive numerical study of thermal elastohydrodynamic lubrication performance in axially crowned rollers, based on a full-system finite element approach. Axial crowning has always been introduced to finite line contacts, as a mean for improving film thickness. Its influence on friction has often been overlooked though. The current work reveals that axial crowning has a negative influence on friction, increasing it significantly with respect to the reference case of straight rollers. It is shown that, with increased crowning height (or reduced crowning radius), minimum film thickness is increased, but so is friction. Therefore, film thickness enhancement comes at the expense of a deterioration in friction. Besides, achieving sufficient enhancements in minimum film thickness would require using relatively low crowning radii, which would lead to a substantial increase in friction. The frictional increase is traced back to an overall increase in contact pressures and effective contact area within the lubricating conjunction. It is also shown that, when film thickness is the most critical design parameter, the best compromise between enhanced film thickness and deteriorated friction would be to combine axial crowning with roller-end profiling. However, when friction is the most critical design parameter, a simple roller-end profiling would offer the best compromise.

Improvement of lubrication performance of water lubricated polymer bearing via enlarged axial end bearing diameter

2019 ◽  
Vol 71 (4) ◽  
pp. 564-572
Author(s):  
Fangrui Lv ◽  
Donglin Zou ◽  
Na Ta ◽  
Zhu-Shi Rao
Keyword(s):  
Film Thickness ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Lubrication Performance ◽  
Load Carrying ◽  
Minimum Film Thickness ◽  
The Impact ◽  
Polymer Bearing ◽  
Practical Implications

Purpose The purpose of this paper is to improve the lubrication performance of a water-lubricated polymer bearing with axial grooves, especially enlarge the minimum film thickness. Design/methodology/approach The bearing diameter is enlarged near the axial ends of the journal, with axial openings of a trumpet shape. A numerical model is developed which considers the proposed trumpet-shaped openings, bush deformation and grooves. The generatrix of the trumpet-shaped opening is assumed to be a paraboloid. Three different variations are covered, and the influences of the trumpet-shaped openings’ parameters on the bearing performance are analyzed. Findings The appropriate trumpet-shaped openings at the axial ends effectively increase the minimum film thickness, and the impact of trumpet-shaped openings on load carrying capacity is very small or even negligible. For the water-lubricated polymer bearing with axial grooves analyzed in this paper, the appropriate trumpet-shaped openings increase the minimum film thickness from 0.53 to 11.14 µm and decrease the load carrying capacity by 2.48 per cent. Practical implications The results of this study can be applied to marine propeller shaft systems and other systems with polymer bearings. Originality/value This paper has presented an approach for significantly increasing the minimum film thickness of a water-lubricated polymer bearing. A study on the performance improvement of water-lubricated polymer bearings with axial grooves is of significant interest to the research community.

An improved TEHL analysis of textured roller bearings consider various texture parameters and slip

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Junning Li ◽  
Ka Han ◽  
Wuge Chen ◽  
Xiaojie Tang ◽  
Qian Wang
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Contact Area ◽  
Surface Texturing ◽  
Elastohydrodynamic Lubrication ◽  
Content Type ◽  
Roller Bearings ◽  
Texture Parameters ◽  
Lubrication Performance ◽  
Texture Size

Purpose The purpose of this study is to reveal the lubrication performance of textured roller bearings under various texture size, texture depth, texture types and slip. Design/methodology/approach In the present study, the improved thermal elastohydrodynamic lubrication method based on the surface texturing of the textured roller bearings is proposed, and then the effect of texture size, texture depth, texture types and slip on the contact pressure, film thickness and temperature distribution are analyzed systematically. Findings The results show that the pressure decreases and the film thickness increases on the contact area because of the surface texturing. The temperature increases first and then decreases as the texture size increases, and then the temperature increases as the texture depth and the slip increases. Compared to circle and square texture, cross texture can obviously decrease the temperature on the contact area. The effectiveness of the proposed method is verified. Originality/value This study can help to reduce friction and wear of textured roller bearings. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2020-0318/

Analysis of the lubricating mechanism for tilting rollers in rolling bearings

2011 ◽  
Vol 225 (11) ◽  
pp. 1059-1070 ◽  
Author(s):  
X-L Liu ◽  
P Yang ◽  
P-R Yang
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Grid Method ◽  
Infinite Plane ◽  
Rolling Bearings ◽  
Velocity Parameter ◽  
Light Load ◽  
Minimum Film Thickness ◽  
Cylindrical Roller ◽  
Lubricating Mechanism

In practice, the tilting roller occurs widely in rolling bearings. In order to investigate the lubricating mechanism of tilting rollers in rolling bearings, a contact between a tilting cylindrical roller and an infinite plane is assumed in the present paper. Using the multi-grid method, a numerical solution has been obtained for the isothermal elastohydrodynamic lubrication of the contact. The film thickness and pressure with different tilt angles have been given. Results show that the property of the tilting roller’s lubrication is different from that of the parallel roller contact investigated in the past, and asymmetry is common both for the film thickness and the oil pressure under tilting conditions. Moreover, the larger the tilt angle, the smaller the minimum film thickness, and the more easily the local wear occurs in bearings. The effects of the maximum Hertzian pressure, velocity parameter, and length and end profile radius of the roller on the lubricating performance of the contact have been discussed. The conclusion can be made that better lubrication of tilting roller contact needs light load, high velocity parameter, short length, and larger end profile radius of the roller. Comparisons between the starved and fully flooded lubrication in the tilting roller contact have been given, and it has been found that starvation status can worsen the lubrication and reduce the life of roller bearings.

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