scholarly journals State of the art of friction modelling at interfaces subjected to elastohydrodynamic lubrication (EHL)

Friction ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 207-227
Author(s):  
Zhuming Bi ◽  
Donald W. Mueller ◽  
Chris W. J. Zhang
Keyword(s):  
State Of The Art ◽  
Computational Modelling ◽  
Elastohydrodynamic Lubrication ◽  
Contact Surfaces ◽  
Friction Prediction ◽  
Hydrodynamic Behaviors ◽  
Lubricant Viscosity ◽  
Film Lubrication ◽  
Friction Modelling ◽  
Fluid Film Lubrication

AbstractElastohydrodynamic lubrication (EHL) is a type of fluid-film lubrication where hydrodynamic behaviors at contact surfaces are affected by both elastic deformation of surfaces and lubricant viscosity. Modelling of contact interfaces under EHL is challenging due to high nonlinearity, complexity, and the multi-disciplinary nature. This paper aims to understand the state of the art of computational modelling of EHL by (1) examining the literature on modeling of contact surfaces under boundary and mixed lubricated conditions, (2) emphasizing the methods on the friction prediction occurring to contact surfaces, and (3) exploring the feasibility of using commercially available software tools (especially, Simulia/Abaqus) to predict the friction and wear at contact surfaces of objects with relative reciprocating motions.

The Effect of Bearing Properties on the Eigenvalues of a Rotordynamic System

2005 ◽  
Author(s):  
Jerry H. Ginsberg ◽  
Benjamin B. Wagner
Keyword(s):  
Rotation Rate ◽  
Damping Ratio ◽  
Cross Sectional ◽  
Campbell Diagram ◽  
Bearing Clearance ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Lubricant Viscosity ◽  
Film Lubrication ◽  
Fluid Film Lubrication

This work examines how the natural frequencies and modal damping ratios of a shaft/rotor system are affected by changes in lubricant viscosity and bearing clearance. The analysis considers a uniform elastic shaft with a single rigid rotor mounted away from mid-span, and supported by fully cavitated, π-film, short-length, plain journal bearings. The transverse displacements and cross-sectional rotations are described by Ritz series, and standard fluid film lubrication theory is used to describe the forces generated by the bearings. The clearance and lubricant viscosity are independently adjustable at each bearing. A Campbell diagram, which depicts the imaginary part of the systems eigenvalues as a function of rotation rate, is used to identify critical speeds for the nominal system. With the rotation rate held fixed at a critical value, lubricant viscosity and bearing clearance are allowed to vary, and the fluctuations of natural frequency and modal damping ratio are evaluated.

An Experimental Study of Friction and Lubrication in Hip Prostheses

1979 ◽  
Vol 8 (3) ◽  
pp. 153-159 ◽  
Author(s):  
J O'Kelly ◽  
A Unsworth ◽  
D Dowson ◽  
V Wright
Keyword(s):  
Experimental Study ◽  
Total Joint Replacement ◽  
Frictional Resistance ◽  
Clinical Situation ◽  
Hip Prostheses ◽  
Hip Function ◽  
Lubricant Viscosity ◽  
Film Lubrication ◽  
Fluid Film Lubrication

McKee-Farrar, Charnley and Muller prostheses have been studied in a hip function simulator using a range of silicone fluids as lubricants. Frictional resistance was measured continuously while the joints were subjected to dynamic loading. It was observed that the lubricant viscosity was very important to the mode of lubrication prevailing and that for viscosities in excess of 0.1 Pas, full fluid film lubrication was achieved. At viscosities which were less than this, mixed lubrication resulted These results can be extrapolated to the clinical situation where it was found that after hip surgery for total joint replacement, the synovial fluid produced around the prosthesis had a viscosity which was less than 0.1 Pas, and therefore could not give the most advantageous lubrication in these joints in vivo.

Effect of Acetabular Cup Design on the Tribology of Metal-on-Metal Hip Resurfacing Replacements: A Contact Mechanics and Elastohydrodynamic Lubrication Study

2005 ◽  
Author(s):  
I. Udofia ◽  
F. Liu ◽  
Z. Jin ◽  
P. Roberts ◽  
P. Grigoris
Keyword(s):  
Contact Mechanics ◽  
Wall Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Hip Resurfacing ◽  
Fluid Film ◽  
Acetabular Cup ◽  
Metal On Metal ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The tribology of metal-on-metal (MOM) hip resurfacing prostheses has been investigated in this study, with particular consideration of the effect of prosthesis design (cup wall thickness and clearance) on the contact mechanics and elastohydrodynamic lubrication (EHL) of these man-made bearings. Two commercially available MOM hip resurfacings, which differ mainly in cup-wall thickness and diametral clearance, were investigated. Finite element contact mechanics and lubrication analyses were carried out on the two MOM hip resurfacing designs. It was found that the thinner acetabular cup with a the relatively smaller clearance resulted in lower contact and hydrodynamic pressure predictions, and a significant increase in the predicted lubricant film thickness at the bearing surfaces. This was attributed to the increase in contact area, conformity between the cup and ball and to the increased influence of the underlying non-metallic structures such as bone and cement, which enhanced the elasticity of the thin acetabular cup. It was shown that full fluid-film lubrication was possible in MOM hip resurfacings during the walking cycle with the small clearance and thin cup-wall thickness model. The importance of the design and manufacturing parameters on the tribological performance of MOM hip resurfacings is highlighted in this study, particularly in promoting fluid film lubrication as a means to further reduce wear at the bearing surfaces.

Paper 3: Recent Developments in Fluid Film Lubrication Theory

1967 ◽  
Vol 182 (1) ◽  
pp. 36-50 ◽  
Author(s):  
T. Lloyd ◽  
H. McCallion
Keyword(s):  
Finite Difference ◽  
High Speed ◽  
Lubrication Theory ◽  
Fluid Film ◽  
Special Topic ◽  
Finite Difference Schemes ◽  
Great Activity ◽  
Wide Range ◽  
Film Lubrication ◽  
Fluid Film Lubrication

Developments in high-speed electronic computers have greatly influenced the progress in fluid film lubrication over the past ten years. Static and dynamic oil film parameters have been computed for a wide range of finite geometries, for hydrostatic and hydrodynamic bearings lubricated by compressible and incompressible lubricants. These are either sufficient in themselves or else act as a yardstick against which approximate formulas may be tested. Much use has been made of iterative finite difference schemes, which are particularly well suited to digital computers, and these methods are now more fully understood. Other methods of solution include direct inversion of finite difference matrices and solution by expression of the pressure by some infinite series, a finite number of terms of which give adequate representation. Besides the increase in design data available, there has been substantial progress through a re-examination of the effects of modifying some of the assumptions inherent in most of the available solutions of the Reynolds equation. These include the assumption of constant lubricant viscosity, of rigid surfaces and of laminar flow. Major progress has been witnessed in two fields. The interaction of the lubricant film with elastic boundaries has been shown to be of prime importance in highly loaded contacts such as gears. This has led to the development of the special topic of elastohydrodynamic lubrication theory. The applicability of gas bearings in such growing industries as computers, space vehicles and nuclear reactors has resulted in great activity and progress in this field.

Film thickness in elastohydrodynamically lubricated slender elliptic contacts: Part I – numerical studies of central film thickness

2021 ◽  
pp. 135065012110477
Author(s):  
Marius Wolf ◽  
Sergey Solovyev ◽  
Fatemi Arshia
Keyword(s):  
Film Thickness ◽  
State Of The Art ◽  
Experimental Studies ◽  
Elastohydrodynamic Lubrication ◽  
Large Parameter ◽  
Numerical Studies ◽  
Minimum Film Thickness ◽  
Subsequent Publication ◽  
New Formula ◽  
Increasing Load

In this paper, analytical equations for the central film thickness in slender elliptic contacts are investigated. A comparison of state-of-the-art formulas with simulation results of a multilevel elastohydrodynamic lubrication solver is conducted and shows considerable deviation. Therefore, a new film thickness formula for slender elliptic contacts with variable ellipticity is derived. It incorporates asymptotic solutions, which results in validity over a large parameter domain. It captures the behaviour of increasing film thickness with increasing load for specific very slender contacts. The new formula proves to be significantly more accurate than current equations. Experimental studies and discussions on minimum film thickness will be presented in a subsequent publication.

Numerical Modeling of Mixed Lubrication and Flash Temperature in EHL Elliptical Contacts

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Neelesh Deolalikar ◽  
Farshid Sadeghi ◽  
Sean Marble
Keyword(s):  
Surface Deformation ◽  
Elastohydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Lubrication Regime ◽  
Predicting Performance ◽  
Pure Rolling ◽  
Rolling Element ◽  
Contact Pressures ◽  
Film Lubrication

Highly loaded ball and rolling element bearings are often required to operate in the mixed elastohydrodynamic lubrication regime in which surface asperity contact occurs simultaneously during the lubrication process. Predicting performance (i.e., pressure, temperature) of components operating in this regime is important as the high asperity contact pressures can significantly reduce the fatigue life of the interacting components. In this study, a deterministic mixed lubrication model was developed to determine the pressure and temperature of mixed lubricated circular and elliptic contacts for measured and simulated surfaces operating under pure rolling and rolling/sliding condition. In this model, we simultaneously solve for lubricant and asperity contact pressures. The model allows investigation of the condition and transition from boundary to full-film lubrication. The variation of contact area and load ratios is examined for various velocities and slide-to-roll ratios. The mixed lubricated model is also used to predict the transient flash temperatures occurring in contacts due to asperity contact interactions and friction. In order to significantly reduce the computational efforts associated with surface deformation and temperature calculation, the fast Fourier transform algorithm is implemented.

The breakdown of fluid film lubrication in elastic-isoviscous point contacts

Wear ◽  
1980 ◽  
Vol 63 (1) ◽  
pp. 25-40 ◽  
Author(s):  
J.B. Medley ◽  
A.B. Strong ◽  
R.M. Pilliar ◽  
E.W. Wong
Keyword(s):  
Fluid Film ◽  
Point Contacts ◽  
Film Lubrication ◽  
Fluid Film Lubrication

Observation of Wall Slip in Elastohydrodynamic Lubrication

1990 ◽  
Vol 112 (3) ◽  
pp. 447-452 ◽  
Author(s):  
M. Kaneta ◽  
H. Nishikawa ◽  
K. Kameishi
Keyword(s):  
Experimental Technique ◽  
Elastohydrodynamic Lubrication ◽  
Wall Slip ◽  
Optical Interferometry ◽  
Stepping Motor ◽  
Ehd Lubrication ◽  
Pure Rolling ◽  
Direct Indication ◽  
Contact Surfaces ◽  
Oil Films

A new experimental technique using optical interferometry has been developed to obtain a direct indication of non-Newtonian response of an oil film under conditions of elastohydrodynamic (EHD) lubrication. A glass disk or a steel ball has been driven by a stepping motor so that crescent-shaped thick oil films with undulation in thickness along the direction of motion have been generated. The experiments have been carried out under pure rolling and pure sliding conditions. It has been found that the oil in an EHD contact behaves like a solid and slips at or near the contact surfaces.

A New Postulation of Viscosity and Its Application in Computation of Film Thickness in TFL1

2002 ◽  
Vol 124 (4) ◽  
pp. 811-814 ◽  
Author(s):  
Chaohui Zhang ◽  
Jianbin Luo ◽  
Shizhu Wen
Keyword(s):  
Thin Film ◽  
Experimental Data ◽  
Film Thickness ◽  
Solid Surface ◽  
Contact Area ◽  
Elastohydrodynamic Lubrication ◽  
Thin Film Lubrication ◽  
Lubrication Film ◽  
Viscosity Modification ◽  
Film Lubrication

In this paper, a viscosity modification model is developed which can be applied to describe the thin film lubrication problems. The viscosity distribution along the direction normal to solid surface is approached by a function proposed in this paper. Based on the formula, lubricating problem of thin film lubrication (TFL) in isothermal and incompressible condition is solved and the outcome is compared to the experimental data. In thin film lubrication, according to the computation outcomes, the lubrication film thickness is much greater than that in elastohydrodynamic lubrication (EHL). When the velocity is adequately low (i.e., film thickness is thin enough), the pressure distribution in the contact area is close to Hertzian distribution in which the second ridge of pressure is not obvious enough. The film shape demonstrates the earlobe-like form in thin film lubrication, which is similar to EHL while the film is comparatively thicker. The transformation relationships between film thickness and loads, velocities or atmosphere viscosity in thin film lubrication differ from those in EHL so that the transition from thin film lubrication to EHL can be clearly seen.

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