scholarly journals Discussion: “Elastohydrodynamic Lubrication of Elliptical Contacts for Materials of Low Elastic Modulus I—Fully Flooded Conjunction” (Hamrock, Bernard J., and Dowson, Duncan, 1978, ASME J. Lubr. Technol., 100, pp. 236–245)

1978 ◽  
Vol 100 (2) ◽  
pp. 245-245
Author(s):  
V. Castelli
Keyword(s):  
Elastic Modulus ◽  
Elastohydrodynamic Lubrication ◽  
Low Elastic Modulus

Elastohydrodynamic Lubrication of Spherical Surfaces of Low Elastic Modulus

1976 ◽  
Vol 98 (4) ◽  
pp. 524-529 ◽  
Author(s):  
S. Biswas ◽  
R. W. Snidle
Keyword(s):  
Elastic Modulus ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Point Contacts ◽  
High Elastic Modulus ◽  
Spherical Surfaces ◽  
Low Elastic Modulus ◽  
Alternative Approach ◽  
Low Modulus ◽  
Theoretical Results

The paper presents a numerical solution for the elastohydrodynamic lubrication of low modulus point contacts which is broadly equivalent to the theory of Grubin for materials of high elastic modulus. The theoretical results obtained for the variation of minimum film thickness using this approach are therefore expected to apply to conditions of high load and low speed. For less severe conditions in which elastic deformation is less significant an alternative approach has been developed. Results of this analysis show the transition from undeformed to heavily loaded conditions. The effect of lubricant starvation has been examined for heavily loaded conditions and the theoretical results are compared with those obtained previously for high elastic modulus point contact.

Mixed lubrication of soft contacts: An engineering look

2016 ◽  
Vol 231 (2) ◽  
pp. 263-273 ◽  
Author(s):  
M Masjedi ◽  
MM Khonsari
Keyword(s):  
Elastic Modulus ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Load Ratio ◽  
Soft Materials ◽  
Line Contact ◽  
Soft Contact ◽  
Lubrication Regime ◽  
Low Elastic Modulus ◽  
Stribeck Curves

Mixed elastohydrodynamic lubrication of materials with low elastic modulus (soft materials) is investigated. Expressions for prediction of film thickness and the asperity load ratio in soft line-contact elastohydrodynamic lubrication are presented. The traction behavior of soft contact in mixed elastohydrodynamic lubrication regime is also studied in terms of the Stribeck curves.

Elastohydrodynamic Lubrication—Improvements in Analytic Solutions

1986 ◽  
Vol 200 (4) ◽  
pp. 281-291 ◽  
Author(s):  
J F Archard ◽  
K P Baglin
Keyword(s):  
Elastic Modulus ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Analytic Solutions ◽  
Physical Explanation ◽  
Inlet Condition ◽  
Low Elastic Modulus ◽  
Tilting Pad ◽  
Computer Analyses ◽  
The Relationship

The paper develops a statement of film shape within an elastohydrodynamic conjunction and shows that the Grubin (parallel conjunction, high elastic modulus) and the Baglin and Archard (tilting pad conjunction, low elastic modulus) models are its asymptotes. A film thickness equation is presented for low values of the parameter N3 = αE′(η0[Formula: see text]/ E′R)1/4. The relationship between inlet pressure [Formula: see text] and maximum Hertzian pressure p0 is explored and it is shown that [Formula: see text]/p0 is primarily a function of N3. Evaluation of the modified inlet condition, [Formula: see text] = (1/α)(1 − e−α[Formula: see text]), allows a limit to be placed on the validity of the Grubin model and provides a physical explanation for the differences between the Grubin and the Dowson and Higginson formulae for film thickness. In this way it is shown that, although film thickness may be evaluated to within a few per cent by the condition [Formula: see text] = 1/α, it does not follow that the conjuction is parallel or that [Formula: see text] = ∞. The model thus provides a link between the simpler analytic theories of elastohydrodynamic lubrication and those based on computer analyses.

Water Lubricated Bearing Lubrication Model Based on Multilayer Gridding

2011 ◽  
Vol 101-102 ◽  
pp. 623-627
Author(s):  
Jin Min Peng ◽  
Jiang Bo Yu
Keyword(s):  
Elastic Modulus ◽  
Numerical Calculation ◽  
Numerical Model ◽  
Elastohydrodynamic Lubrication ◽  
Water Film ◽  
Contact Theory ◽  
Frictional Surface ◽  
Model Based ◽  
Low Elastic Modulus ◽  
High Elasticity

The principle of the multilayer gridding algorithm, as well as its applications to the numerical calculation of water lubricated plastic alloy bearing elastohydrodynamic lubrication (EHL), was described. The computation of water lubricated plastic alloy bearing EHL was carried out by the numerical model based on the linear contact theory. A cuneiform water film on the frictional surface between bearing and spindle is formed because the plastic alloy has a high elasticity and low elastic modulus, which lead the water lubricated bearing easy to be distorted.

Nondimensional Presentation of Frictional Tractions in Elastohydrodynamic Lubrication—Part II: Starved Conditions

1975 ◽  
Vol 97 (3) ◽  
pp. 412-421 ◽  
Author(s):  
J. F. Archard ◽  
K. P. Baglin
Keyword(s):  
Elastic Modulus ◽  
Film Thickness ◽  
Sliding Friction ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Friction ◽  
Analytic Treatment ◽  
Low Elastic Modulus ◽  
Pressure Dependent Viscosity ◽  
Dependent Viscosity ◽  
Negligible Influence

Part I of this paper presented a broad semi-analytic treatment of frictional tractions in nondimensional terms; this was confined to the fully flooded situation and the present paper extends the analysis to include starved conditions. As in Part I three major conditions are considered in detail: classical (isoviscous, undeformed) low elastic modulus (isoviscous, heavily deformed) and high elastic modulus (pressure dependent viscosity, heavily deformed). The influence of starvation is presented as a series of correction curves for the rolling and sliding friction derived for fully flooded conditions. Starvation influences friction both through the extent to which the gap between the surfaces is filled by lubricant and through its influence upon the film thickness. Both factors affect rolling friction which is therefore markedly reduced by starvation so mild that there is negligible influence upon the film thickness. In contrast, sliding friction (arising either in the main pressure zone or the cavitated region) is most strongly influenced by the film thickness and is therefore markedly affected only by relatively severe starvation.

Elastohydrodynamic Lubrication of Elliptical Contacts for Materials of Low Elastic Modulus: II—Starved Conjunction

1979 ◽  
Vol 101 (1) ◽  
pp. 92-98 ◽  
Author(s):  
B. J. Hamrock ◽  
D. Dowson
Keyword(s):  
Elastic Modulus ◽  
Film Thickness ◽  
Rolling Direction ◽  
Numerical Procedure ◽  
Elastohydrodynamic Lubrication ◽  
Radius Of Curvature ◽  
Low Elastic Modulus ◽  
Minimum Film Thickness ◽  
Contour Plots ◽  
Lubrication Conditions

By using the theory and numerical procedure developed by the authors in earlier publications, the influence of lubricant starvation upon minimum film thickness in starved elliptical elastohydrodynamic conjunctions for low-elastic-modulus materials has been investigated. Lubricant starvation was studied simply by moving the inlet boundary closer to the center of the conjunction. The results show that the location of the dimensionless inlet boundary m* between the fully flooded and starved conditions can be expressed simply as m* = 1 + 1.07 [(Rx/b)2Hmin,F]0.16, where Rx is the effective radius of curvature in the rolling direction, b is the semiminor axis of the contact ellipse, and Hmin,F is the dimensionless mimimum film thickness for the fully flooded condition. That is, for a dimension-less inlet distance m less than m*, starvation occurs; and for m ≥ m*, a fully flooded condition exists. Furthermore, it has been possible to express the minimum film thickness for a starved condition as Hmin,S = Hmin,F [(m − 1)/(m* − 1)]0.22. Contour plots of the pressure and film thickness in and around the contact are presented for both the fully flooded and starved lubrication conditions. It is evident from the contour plots that the inlet pressure contours become less circular and that the film thickness decreases substantially as the severity of starvation increases. The results presented in this report, when combined with the findings previously reported, enable the essential features of starved, elliptical, elastohydrodynamic conjunctions for materials of low elastic modulus to be ascertained.

Elastohydrodynamic Lubrication of Elliptical Contacts for Materials of Low Elastic Modulus I—Fully Flooded Conjunction

1978 ◽  
Vol 100 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Bernard J. Hamrock ◽  
Duncan Dowson
Keyword(s):  
Elastic Modulus ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Elastohydrodynamic Lubrication ◽  
Line Contact ◽  
Low Elastic Modulus ◽  
Minimum Film Thickness ◽  
Contour Plots ◽  
Order Of Magnitude ◽  
Ellipticity Parameter

Our earlier studies of elastohydrodynamic lubrication of conjunctions of elliptical form are applied to the particular and interesting situation exhibited by materials of low elastic modulus. By modifying the procedures we outlined in an earlier publication, the influence of the ellipticity parameter k and the dimensionless speed U, load W, and material G parameters on minimum film thickness for these materials has been investigated. The ellipticity parameter was varied from 1 (a ball-on-plate configuration) to 12 (a configuration approaching a line contact). The dimensionless speed and load parameters were varied by 1 order of magnitude. Seventeen different cases were used to generate the following minimum- and central-film-thickness relations: H˜min=7.43(1−0.85e−0.31k)U0.65W−0.21H˜c=7.32(1−0.72e−0.28k)U0.64W−0.22 Contour plots are presented that illustrate in detail the pressure distribution and film thickness in the conjunction.

Nondimensional Presentation of Frictional Tractions in Elastohydrodynamic Lubrication—Part I: Fully Flooded Conditions

1975 ◽  
Vol 97 (3) ◽  
pp. 398-410 ◽  
Author(s):  
J. F. Archard ◽  
K. P. Baglin
Keyword(s):  
Elastic Modulus ◽  
Elastohydrodynamic Lubrication ◽  
Analytic Solutions ◽  
Glassy Polymers ◽  
Exponential Relationship ◽  
Low Elastic Modulus ◽  
Pressure Dependent Viscosity ◽  
Wide Range ◽  
Computer Based ◽  
Dependent Viscosity

Using several sources, analytic and semi-analytic solutions for frictional tractions of a lubricated line contact are presented in the appropriate non-dimensional form which is similar to that previously used by Moes for film thickness. A Newtonian lubricant with an exponential relationship between viscosity and pressure is assumed and, at this stage, the treatment is confined to fully flooded conditions. The components of frictional tractions arising from rolling (Poisseiulle) and sliding (Couette) flows are distinguished and sliding tractions in the outlet cavitated region are separated from those in the main pressure zone. Three main regimes of lubrication are studied: classical (isoviscous, undeformed), low elastic modulus (isoviscous, heavily deformed) and high elastic modulus (pressure dependent viscosity, heavily deformed). The results presented here provide a broad background of approximate results, covering a very wide range of conditions against which the results of more precise computer-based analyses can be judged. Thus the treatment reveals the existence of a range of conditions (typical of the lubrication of glassy polymers by hydrocarbon lubricants) which has been little studied and is, as yet, imperfectly understood.

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