Discussion: “A Film Thickness Analysis for Line Contacts Under Pure Rolling Conditions With a Non-Newtonian Rheological Model” (Gecim, B., and Winer, W. O., 1981, ASME J. Lubr. Technol., 103, pp. 305–313)

1981 ◽  
Vol 103 (2) ◽  
pp. 313-314
Author(s):  
B. Jacobsson
Keyword(s):  
Film Thickness ◽  
Rheological Model ◽  
Pure Rolling ◽  
Line Contacts

A Film Thickness Analysis for Line Contacts Under Pure Rolling Conditions With a Non-Newtonian Rheological Model

1981 ◽  
Vol 103 (2) ◽  
pp. 305-313 ◽  
Author(s):  
B. Gecim ◽  
W. O. Winer
Keyword(s):  
Shear Stress ◽  
Film Thickness ◽  
High Viscosity ◽  
Low Viscosity ◽  
Limiting Shear Stress ◽  
Lubrication Regime ◽  
Pure Rolling ◽  
Reasonable Range ◽  
Line Contacts ◽  
Rolling Elements

The non-Newtonian constitutive equation proposed by Winer and Bair [1] is applied in a conventional isothermal film thickness analysis of line contact lubrication of rolling elements. The present analysis provides four different dimensionless film thickness equations for four different regimes of lubrication. Due to the formulation technique used in deriving the governing pressure-gradient equation, the present study is recommended for high viscosity, high rolling speed, and low limiting shear stress cases where Newtonian models fail to match the experimental data. Comparison of the present film thickness equations with the Newtonian correspondences in each lubrication regime shows a considerable difference, but the analysis suffers from the fact that the limiting shear stress parameters of these high viscosity lubricants need to be determined experimentally. The present analysis assumes a reasonable range of limiting shear stress which is smaller than the corresponding values for low viscosity lubricants which are predominantly Newtonian in behavior (unless severe rolling and/or sliding with high loads is applied).

A Full Numerical EHL Solution for Line Contacts Under Pure Rolling Condition With a Non-Newtonian Rheological Model

1988 ◽  
Vol 110 (4) ◽  
pp. 583-586 ◽  
Author(s):  
S. H. Wang ◽  
D. Y. Hua ◽  
H. H. Zhang
Keyword(s):  
Power Law ◽  
Rheological Model ◽  
Surface Deformation ◽  
Power Law Model ◽  
Lubrication Equation ◽  
Pressure Distributions ◽  
Pure Rolling ◽  
Power Law Exponent ◽  
Line Contacts ◽  
Tangent Method

The rheological effects of lubricants and the surface deformation of disks are considered in the lubrication of line contacts. The lubrication equation for fluids obeying power law model has been derived. The lubrication equation and the elastic equation have been solved simultaneously within the contact zone by means of the Newton-tangent method. Pressure distributions and film profiles are obtained. The results of this paper show that with the increase of the power law exponent n, the oil film becomes thicker and the position of the cavitation point moves closer to the center of contact.

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.

Grease soap particles passing through an elastohydrodynamic contact under side slip conditions

2000 ◽  
Vol 214 (4) ◽  
pp. 317-325 ◽  
Author(s):  
P Eriksson ◽  
V Wikström ◽  
R Larsson
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Previous Investigation ◽  
Video Camera ◽  
Slip Conditions ◽  
High Speed Video ◽  
Elastohydrodynamic Contact ◽  
High Speed Video Camera ◽  
Pure Rolling ◽  
Minimum Film Thickness

In a previous investigation, grease thickener fibres were tracked as they passed through an elastohydrodynamic (EHD) contact in pure rolling using interferometry in a standard ball-and-disc apparatus. In order to capture single thickener fibres, a high-speed video camera was used. Here, the experiments have been repeated introducing different amounts of side slip for different rolling speeds and a faster video camera capable of capturing 4500 frames/s. The contact was lubricated with a continuous supply of grease. Two greases, based on the same synthetic poly(α-olefin) but thickened with Li-12-OH and lithium complex soap respectively, were studied. It was observed that the thickener fibres were stretched both before entering the contact and as they passed through it. Fibres seem to avoid the minimum film thickness regions and, if they enter, the film is restored immediately after passage.

scholarly journals A Quantitative Determination of Minimum Film Thickness in Elastohydrodynamic Circular Contacts

2021 ◽  
Author(s):  
Wassim Habchi ◽  
Philippe Vergne
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Numerical Model ◽  
Film Thickness ◽  
Quantitative Determination ◽  
Excellent Agreement ◽  
Operating Conditions ◽  
Pure Rolling ◽  
Minimum Film Thickness

Abstract The current work presents a quantitative approach for the prediction of minimum film thickness in elastohydrodynamic lubricated (EHL) circular contacts. In contrast to central film thickness, minimum film thickness can be hard to accurately measure, and it is usually poorly estimated by classical analytical film thickness formulae. For this, an advanced finite-element-based numerical model is used to quantify variations of the central-to-minimum film thickness ratio with operating conditions, under isothermal Newtonian pure-rolling conditions. An ensuing analytical expression is then derived and compared to classical film thickness formulae and to more recent similar expressions. The comparisons confirmed the inability of the former to predict the minimum film thickness, and the limitations of the latter, which tend to overestimate the ratio of central-to-minimum film thickness. The proposed approach is validated against numerical results as well as experimental data from the literature, revealing an excellent agreement with both. This framework can be used to predict minimum film thickness in circular elastohydrodynamic contacts from knowledge of central film thickness, which can be either accurately measured or rather well estimated using classical film thickness formulae.

Effects of polymers concentration on EHL film-forming in point contacts

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liangwei Qiu ◽  
Xiaoyang Chen ◽  
Fakai Dong
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Point Contact ◽  
High Concentration ◽  
Content Type ◽  
Base Oils ◽  
Low Viscosity ◽  
Lubricant Oil ◽  
Pure Rolling ◽  
Film Forming

Purpose This paper aims to experimentally investigate the film-forming capability of base oils containing poly-methacrylate (PMA) and poly-isobutene (PIB), in a point contact under pure rolling. Design/methodology/approach By using the relative light intensity method, the film thickness is calculated from the interferometer images which are captured by multiple-contact optical elastohydrodynamic lubricated test rig. Findings The test results reveal that polymers, both PMA and PIB, have a significant contribution to the film-forming capability of base oils and the film thickness increases with concentration. The forming-film capabilities for PMA and PIB in base oils are similar at low concentration, while PIB gives a higher film thickness than PMA at high concentration. Shear-thinning phenomenon are observed in all polymer-based oils. Originality/value The polymer usually as an additive is added into the low viscosity base oils to improve the properties of lubricant oil. This paper reports the lubricated properties of PMA and PIB with different concentrations in base oils and to evaluate their functional mechanism in a point contact. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0263/

Prediction of Traction in Sliding EHD Contacts

1976 ◽  
Vol 98 (3) ◽  
pp. 362-365 ◽  
Author(s):  
R. Kunz ◽  
W. O. Winer
Keyword(s):  
Shear Stress ◽  
Film Thickness ◽  
Surface Temperature ◽  
Material Properties ◽  
Rheological Model ◽  
Normal Load ◽  
Point Contact ◽  
Temperature Data ◽  
Stress Theory ◽  
Surface Temperature Data

An existing shear stress theory and lubricant rheological model were studied and evaluated by applying them to traction prediction in a sliding elastohydrodynamic point contact. Numerical calculations, using measured film thickness and surface temperature data, were compared with measured tractions under several conditions of normal load and sliding speed. In addition, the theory was used to study the effect on the traction of variations in the lubricant material properties.

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