Reflections on Some Aspects of Lubrication of Concentrated Line Contacts

1979 ◽  
Vol 101 (4) ◽  
pp. 528-531 ◽  
Author(s):  
P. H. Markho ◽  
D. B. Clegg
Keyword(s):  
Film Thickness ◽  
Curve Fitting ◽  
Line Contact ◽  
Intermediate Region ◽  
Force Component ◽  
Pressure Force ◽  
Tangential Pressure ◽  
Method Of Least Squares ◽  
End Conditions ◽  
Line Contacts

New formulas are presented for two important lubrication parameters of a flooded, concentrated line contact, namely the tangential pressure force component under elasto-hydrodynamic (EHD) conditions and the film thickness in the “intermediate” region defined by Dowson and Whitaker [1]. The latter region, which separates the rigid-isoviscous region from the elastic-piezoviscous (or EHD) region, has not, so far, been represented by an equation. The first formula was obtained simply by curve-fitting, using the method of least squares, from data largely available in the published literature; while the second is basically a third degree Hermite osculating polynomial with four end conditions.

Simple Formulas for Performance Parameters Used in Elastohydrodynamically Lubricated Line Contacts

1989 ◽  
Vol 111 (2) ◽  
pp. 246-251 ◽  
Author(s):  
Ping Pan ◽  
B. J. Hamrock
Keyword(s):  
Film Thickness ◽  
Curve Fitting ◽  
Center Of Pressure ◽  
Operating Parameters ◽  
Performance Parameters ◽  
Practical Applications ◽  
Line Contacts ◽  
Pressure Spike

The film thickness and pressure in elastohydrodynamically lubricated conjunctions have been evaluated numerically for a rather complete range of operating parameters (dimensionless load, speed, and materials parameters) normally experienced in practical applications. From the film thickness and pressure throughout the conjunction a number of performance parameters were evaluated. By curve fitting the data, formulas were obtained that allow easy evaluation of the amplitude and location of the pressure spike, the minimum and central film thicknesses, the value of ρeHe, and the center of pressure.

Numerical Analysis for Influence of Plastic and Elastic Deformation of Rough Surfaces on PEHL for Line Contacts

Tribology ◽  
2005 ◽  
Author(s):  
R. J. Niu ◽  
P. Huang
Keyword(s):  
Plastic Deformation ◽  
Film Thickness ◽  
Hydrodynamic Lubrication ◽  
Paper Analysis ◽  
Line Contact ◽  
Plastic Deformations ◽  
Rolling Contacts ◽  
Line Contacts ◽  
Elastic And Plastic Deformations ◽  
Strain Relationship

In the present paper, analysis of elasto-plasto-hydrodynamic lubrication (PEHL) in the line contact is carried out to investigate the effect of heavily loaded roll-over on the change in profile of indents. The pressure and film thickness profiles are obtained to solve the Reynolds and film thickness equations simultaneously. And, both the elastic and plastic deformations of the contact, featured with an indent, have been considered. A multi-grid numerical algorithm used in EHL of line contacts is modified and then used for the oil lubricated rolling contacts. In the program, stress and plastic deformation of the indent profile are calculated with the hardening plastic stress-strain relationship according to the theories of plasticity when pressure excesses the yield stress. The results, with and without considering plastic deformation, are compared to show the different influences on the pressure and film thickness. Analysis shows that since the plastic deformation will change the surface roughness, it will significantly change the pressure but film thickness.

Estimation of Minimum Thickness for Line Contacts in the Transition Region between the Isoviscous—Elastic and the Piezoviscous-Elastic Lubrication Regimes

1989 ◽  
Vol 203 (6) ◽  
pp. 379-386 ◽  
Author(s):  
M J Jaffar
Keyword(s):  
Film Thickness ◽  
Transition Region ◽  
Approximate Formula ◽  
Line Contact ◽  
Minimum Thickness ◽  
Lubrication Regimes ◽  
Minimum Film Thickness ◽  
Line Contacts ◽  
Good Agreement

This paper represents a solution for lubricated cylinders in line contact operating in the transition region between isoviscous-elastic and piezoviscous-elastic conditions. The computer solutions are used to generate a formula for the minimum film thickness. The approximate formula is compared with the existing formulae at the boundaries of the lubrication regimes where good agreement is obtained. Also, the influence of the starvation on pressure and film thickness is investigated.

scholarly journals Effect of an Improved Yasutomi Pressure-Viscosity Relationship on the Elastohydrodynamic Line Contact Problem

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Vincenzo Petrone ◽  
Adolfo Senatore ◽  
Vincenzo D'Agostino
Keyword(s):  
High Pressure ◽  
Film Thickness ◽  
Free Volume ◽  
Experimental Studies ◽  
Line Contact ◽  
Volume Model ◽  
Free Volume Model ◽  
Pressure Area ◽  
New Formulation ◽  
Lubricant Viscosity

This paper presents the application of an improved Yasutomi correlation for lubricant viscosity at high pressure in a Newtonian elastohydrodynamic line contact simulation. According to recent experimental studies using high pressure viscometers, the Yasutomi pressure-viscosity relationship derived from the free-volume model closely represents the real lubricant piezoviscous behavior for the high pressure typically encountered in elastohydrodynamic applications. However, the original Yasutomi correlation suffers from the appearance of a zero in the function describing the pressure dependence of the relative free volume thermal expansivity. In order to overcome this drawback, a new formulation of the Yasutomi relation was recently developed by Bair et al. This new function removes these concerns and provides improved precision without the need for an equation of state. Numerical simulations have been performed using the improved Yasutomi model to predict the lubricant pressure-viscosity, the pressure distribution, and the film thickness behavior in a Newtonian EHL simulation of a squalane-lubricated line contact. This work also shows that this model yields a higher viscosity at the low-pressure area, which results in a larger central film thickness compared with the previous piezoviscous relations.

scholarly journals Optical Analysis of Ball Bearing Starvation

1971 ◽  
Vol 93 (3) ◽  
pp. 349-361 ◽  
Author(s):  
L. D. Wedeven ◽  
D. Evans ◽  
A. Cameron
Keyword(s):  
Film Thickness ◽  
Ball Bearing ◽  
Point Contact ◽  
Experimental Measurements ◽  
Line Contact ◽  
Optical Analysis ◽  
Grease Lubrication ◽  
Theoretical Predictions ◽  
Pressure Stress ◽  
Starvation Conditions

Elastohydrodynamic oil film measurements for rolling point contact under starvation conditions are obtained using optical interferometry. The experimental measurements present a reasonably clear picture of the starvation phenomenon and are shown to agree with theoretical predictions. Starvation inhibits the generation of pressure and, therefore, reduces film thickness. It also causes the overall pressure, stress, and elastic deformation to become more Hertzian. Additional experiments using interferometry illustrate: the cavitation pattern, lubricant entrapment, grease lubrication, ball spin, and edge effects in line contact.

Effect of Rolling Velocity and Maximum Hertzian Pressure on Fluid Film in Steady State EHL Line Contact with Rough Surface and Linear Piezoviscosity

2014 ◽  
Vol 592-594 ◽  
pp. 1371-1375
Author(s):  
Nitesh Talekar ◽  
Punit Kumar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Film Thickness ◽  
Rough Surface ◽  
Computer Code ◽  
Fluid Film ◽  
Line Contact ◽  
Rolling Velocity ◽  
Load Carrying ◽  
Lubricated Contact

Consideration of surface roughness in steady state EHL line contact is the first step towards understanding the lubrication of rough surface problem. Current paper investigates the use of sinusoidal waviness in the contact; more precisely it gives performance of real fluid in EHL line contact. The effect of various parameters like rolling velocity (U) and maximum Hertzian pressure (ph) on surface roughness by using properties of linear and exponential piezo-viscosity is taken into consideration to evaluate behavior of pressure distribution of load carrying fluid film and film thickness. Full isothermal, Newtonian simulation of EHL problem gives described effects. Spiking or fluctuation of pressure and film thickness curves is expected to show presence of irregularities on the surface chosen and amount of fluctuation depends on certain parameters and intensity of irregularities present. Rolling side domain of-4.5 ≤ X ≤ 1.5 with grid size ∆X=0.01375 is selected. A computer code is developed to solve Reynolds equation, which governs the generation of pressure in the lubricated contact zone is discritized and solved along with load balance equation using Newton-Raphson technique.

Simulation of Plasto-Elastohydrodynamic Lubrication in Line Contacts of Infinite and Finite Length

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Tao He ◽  
Jiaxu Wang ◽  
Zhanjiang Wang ◽  
Dong Zhu
Keyword(s):  
Surface Roughness ◽  
Finite Length ◽  
3D Model ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Axial Direction ◽  
Contact Length ◽  
Line Contact ◽  
Line Contacts ◽  
3D Surface Topography

Line contact is common in many machine components, such as various gears, roller and needle bearings, and cams and followers. Traditionally, line contact is modeled as a two-dimensional (2D) problem when the surfaces are assumed to be smooth or treated stochastically. In reality, however, surface roughness is usually three-dimensional (3D) in nature, so that a 3D model is needed when analyzing contact and lubrication deterministically. Moreover, contact length is often finite, and realistic geometry may possibly include a crowning in the axial direction and round corners or chamfers at two ends. In the present study, plasto-elastohydrodynamic lubrication (PEHL) simulations for line contacts of both infinite and finite length have been conducted, taking into account the effects of surface roughness and possible plastic deformation, with a 3D model that is needed when taking into account the realistic contact geometry and the 3D surface topography. With this newly developed PEHL model, numerical cases are analyzed in order to reveal the PEHL characteristics in different types of line contact.

scholarly journals Fast Approach for Calculating Film Thicknesses and Pressures in Elastohydrodynamically Lubricated Contacts at High Loads

1986 ◽  
Vol 108 (3) ◽  
pp. 411-419 ◽  
Author(s):  
L. G. Houpert ◽  
B. J. Hamrock
Keyword(s):  
High Pressure ◽  
Film Thickness ◽  
Line Contact ◽  
Elastic Deformations ◽  
New Approach ◽  
Lubricated Contacts ◽  
Fast Approach ◽  
Pressure Spike

The film thicknesses and pressures in elastohydrodynamically lubricated contacts have been calculated for a line contact by using an improved version of Okamura’s approach. The new approach allows for lubricant compressibility, the use of Roelands viscosity, a general mesh (nonconstant step), and accurate calculations of the elastic deformations. The new approach is described, and the effects on film thickness, pressure, and pressure spike of each of the improvements are discussed. Successful runs have been obtained at high pressure (to 4.8 GPa) with low CPU times.

Experimental study on line-contact elastohydrodynamic grease lubrication properties of surface-textured rollers

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fuqin Yang ◽  
Dexing Hu ◽  
Qianhao Xiao ◽  
Shun Zhao
Keyword(s):  
Film Thickness ◽  
Surface Texture ◽  
Inhibitory Effect ◽  
Lubricating Oil ◽  
Line Contact ◽  
Grease Lubrication ◽  
Content Type ◽  
Oil Film ◽  
Crown Width ◽  
Lubrication Properties

Purpose This paper aims to study line-contact elastohydrodynamic grease lubrication properties of surface-textured rollers as well as the effect of different crown widths (dw) on oil film thickness under textured conditions. Design/methodology/approach The laser processing method was used to make the micro-texture on the surface of GCr15 steel rollers; lithium grease was used as the lubricant, and line-contact elastohydrodynamic grease lubrication experiments under pure sliding conditions were performed on light interference elastohydrodynamic-lubricated experimental table. Findings The results show that the line-contact elastohydrodynamic grease lubrication is closely related to the textured crown width of steel rollers. At low speeds and light loads, texturing has an inevitable inhibitory effect on the formation of the lubricating oil film, and the smaller the width of the crown area, the more obvious the inhibitory effect, which is not conducive to the improvement of the lubrication condition. At high speeds and high loads, the textured roller with dw = 1 mm has the largest oil film thickness and shows better lubrication performance. Originality/value At present, there is little research on the surface texture of line-contact friction pairs. This work explores the effect of different textured crown width on the lubricating properties of line-contact elastohydrodynamic grease lubrication by experiment. It provides a new theoretical basis for the subsequent practical application of surface texture technology.

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