Rheological Effects On Friction In Elastohydrodynamic Lubrication

Author : Edward G. Trachman,Herbert S. Cheng
Publisher : Unknown
Page : 220 pages
File Size : 40,8 Mb
Release : 1973
Category : Fluid-film bearings
ISBN : UIUC:30112106680157

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Rheological Effects on Friction in Elastohydrodynamic Lubrication by Edward G. Trachman,Herbert S. Cheng Pdf

An analytical and experimental investigation is presented of the friction in a rolling and sliding elastohydrodynamic lubricated contact. The rheological behavior of the lubricant is described in terms of two viscoelastic models. These models represent the separate effects of non-Newtonian behavior and the transient response of the fluid. A unified description of the non-Newtonian shear rate dependence of the viscosity is presented as a new hyperbolic liquid model. The transient response of viscosity, following the rapid pressure rise encountered in the contact, is described by a compressional viscoelastic model of the volume response of a liquid to an applied pressure step. The resulting momentum and energy equations are solved by an iterative numerical technique, and a friction coefficient is calculated. The experimental study was performed, with two synthetic paraffinic lubricants, to verify the friction predictions of the analysis. The values of friction coefficient from theory and experiment are in close agreement.

Author : B.O. Jacobson
Publisher : Elsevier
Page : 381 pages
File Size : 47,7 Mb
Release : 1991-07-24
Category : Science
ISBN : 0080875831

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Rheology and Elastohydrodynamic Lubrication by B.O. Jacobson Pdf

This book gives a thorough overview on recent developments in lubricant rheology, elastohydrodynamic lubrication and the effects of surface roughness and particulate contamination in the lubricant on the overall behaviour of a heavily loaded lubricated contact. One of the aims of the book is to make clear to the reader that a Newtonian model for the lubricant behaviour does not have enough degrees of freedom to be able to describe the friction - traction behaviour of heavily loaded lubricated contacts or the oil film build-up and collapse under surface asperities for rough surfaces. The book contains quite a lot of experimental data of lubricants at high pressures, both solidification pressures, compressibilities and shear strength increase coefficients, which make it possible to estimate the friction and power loss in heavily loaded lubricated contacts for different pressures, temperatures, sliding speeds, and lubricant types. This is the first time that data of this type has been included in a textbook and it is hoped that the questions highlighted will serve to initiate and guide future research in this field.

Author : Scott S Bair
Publisher : Elsevier
Page : 260 pages
File Size : 41,5 Mb
Release : 2007-03-06
Category : Technology & Engineering
ISBN : 0080475302

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High Pressure Rheology for Quantitative Elastohydrodynamics by Scott S Bair Pdf

Computational elastohydrodynamics, a part of tribology, has existed happily enough for about fifty years without the use of accurate models for the rheology of the liquids used as lubricants. For low molecular weight liquids, such as low viscosity mineral oils, it has been possible to calculate, with precision, the film thickness in a concentrated contact provided that the pressure and temperature are relatively low, even when the pressure variation of viscosity is not accurately modelled in detail. Other successes have been more qualitative in nature, using effective properties which come from the fitting of parameters used in calculations to experimental measurements of the contact behaviour, friction or film thickness. High Pressure Rheology for Quantitative Elastohydrodynamics is intended to provide a sufficiently accurate framework for the rheology of liquids at elevated pressure that it may be possible for computational elastohydrodynamics to discover the relationships between the behaviour of a lubricated concentrated contact and the measurable properties of the liquid lubricant. The required high-pressure measurement techniques are revealed in detail and data are presented for chemically well-defined liquids that may be used as quantitative reference materials. * Presents the property relations required for a quantitative calculation of the tribological behaviour of lubricated concentrated contacts. * Details of high-pressure experimental techniques. * Complete description of the pressure and temperature dependence of viscosity for high pressures. * Some little-known limitations on EHL modelling.

Author : D. Dowson,G. R. Higginson
Publisher : Elsevier
Page : 254 pages
File Size : 51,9 Mb
Release : 2014-07-18
Category : Technology & Engineering
ISBN : 9781483181899

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Elasto-Hydrodynamic Lubrication by D. Dowson,G. R. Higginson Pdf

Elasto-Hydrodynamic Lubrication deals with the mechanism of elasto-hydrodynamic lubrication, that is, the lubrication regime in operation over the small areas where machine components are in nominal point or line contact. The lubrication of rigid contacts is discussed, along with the effects of high pressure on the lubricant and bounding solids. The governing equations for the solution of elasto-hydrodynamic problems are presented. Comprised of 13 chapters, this volume begins with an overview of elasto-hydrodynamic lubrication and representation of contacts by cylinders, followed by a discussion on equations relevant to lubrication, including the Reynolds equation. The reader is then introduced to lubrication of rigid cylinders; the importance of film thickness in highly loaded rigid contacts; the elasticity of solids in contact; and the theory of elasto-hydrodynamic lubrication. Subsequent chapters focus on apparatus and measurements of film thickness and film shape; friction and viscosity; and lubrication of gears and roller bearings. This book will be of interest to tribologists.

Author : A. Dorinson,K.C. Ludema
Publisher : Elsevier
Page : 633 pages
File Size : 54,6 Mb
Release : 1985-08-01
Category : Technology & Engineering
ISBN : 0080875734

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Mechanics and Chemistry in Lubrication by A. Dorinson,K.C. Ludema Pdf

Although it is widely recognized that friction, wear and lubrication are linked together in a single interdisciplinary complex of scientific learning and technological practice, fragmented and specialized approaches still predominate. In this book, the authors examine lubrication from an interdisciplinary viewpoint. They demonstrate that once the treatment of lubrication is released from the confines of the fluid film concept, this interdisciplinary approach comes into full play. Tribological behavior in relation to lubrication is then examined from two major points of view: one is mechanical, not only with respect to the properties and behavior of the lubricant but also of the surfaces being lubricated. The other is chemical and encompasses the chemistry of the lubricant, the surfaces and the ambient surroundings. It is in the emphasis on the interaction of the basic mechanical and chemical processes in lubrication that this book differs from conventional treatments.

Author : D. Dowson,G. R. Higginson
Publisher : Unknown
Page : 264 pages
File Size : 48,6 Mb
Release : 1966
Category : Bearings (Machinery)
ISBN : UCAL:B3756619

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Elasto-hydrodynamic Lubrication by D. Dowson,G. R. Higginson Pdf

Author : Bernard J. Hamrock
Publisher : NASA Office of Management Scientific a
Page : 680 pages
File Size : 47,7 Mb
Release : 1991
Category : Technology & Engineering
ISBN : UIUC:30112004257785

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Fundamentals of Fluid Film Lubrication by Bernard J. Hamrock Pdf

Author : Rahnejat Homer,Gohar Ramsey
Publisher : World Scientific
Page : 520 pages
File Size : 44,8 Mb
Release : 1998-10-20
Category : Technology & Engineering
ISBN : 9781786345196

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Fundamentals of Tribology by Rahnejat Homer,Gohar Ramsey Pdf

Fundamentals of Tribology deals with the fundamentals of lubrication, friction and wear, as well as mechanics of contacting surfaces and their topography. It begins by introducing the reader to the importance of tribology in everyday life and offers a brief history of the subject. It then describes the nature of rough surfaces and the mechanics of contacting elastic solids and their deformation under load and friction in their relative motion. The book goes on to discuss the importance of lubricant rheology with respect to viscosity and density. Then, the principles of hydrodynamic lubrication are covered with derivations of the governing Reynolds and energy equations. Applications of hydrodynamic lubrication in various forms of bearings -- journal bearings, thrust bearings and externally pressurised bearings -- are outlined. The important and still evolving subject of elastohydrodynamic lubrication is treated in some detail, both at its fundamentals and its applications in thin shell or overlay bearings, cam-followers and internal combustion engine pistons. The fundamentals of biotribology are also covered, particularly its applications to endo-articular mammalian joints such as hip and knee joints and their arthroplasty. In addition, there is a treatment of the rapidly emerging knowledge of tribological phenomena in lightly loaded vanishing conjunctions (nanotribology), in natural systems and very small devices, such as MEMS and high density data storage media. There is also a new chapter on the rapidly emerging subject of surface texturing to promote retention of microreservoirs of lubricant, acting as microbearings and improving lubrication of otherwise poorly lubricated conjunctions. This book targets the undergraduate and postgraduate body as well as engineering professionals in industry, where often a quick solution or understanding of certain tribological fundamentals is sought. The book can also form an initial basis for those interested in research into certain aspects of tribology.

Author : Scott S. Bair
Publisher : Elsevier
Page : 388 pages
File Size : 54,8 Mb
Release : 2019-04-18
Category : Technology & Engineering
ISBN : 9780128163108

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High Pressure Rheology for Quantitative Elastohydrodynamics by Scott S. Bair Pdf

High-Pressure Rheology for Quantitative Elastohydrodynamics, Second Edition, contains updated sections on scaling laws and thermal effects, including new sections on the importance of the pressure dependence of viscosity, the role of the localization limit of stress, and new material on the shear dependence of viscosity and temperature dependence viscosity. Since publication of the original edition, the experimental methods, the resulting property data and new correlations have resulted in a revolution in understanding of the mechanisms of film formation and the mechanical dissipation. Describes lubricant rheology and dependence of lubricant viscosity and density on pressure and temperature Provides a detailed description of the relationship of lubricant properties on pressure, temperature and shear stress Includes data for many more liquids, including the recently characterized reference liquids

Author : G. Dalmaz,T.H.C. Childs,D. Dowson,C.M. Taylor
Publisher : Elsevier
Page : 693 pages
File Size : 54,9 Mb
Release : 1995-10-05
Category : Technology & Engineering
ISBN : 0080875947

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Lubricants and Lubrication by G. Dalmaz,T.H.C. Childs,D. Dowson,C.M. Taylor Pdf

These proceedings review progress in the development of lubricants and in the understanding of the phenomena of lubrication. The contents include papers on the impact of automotive technology and environmental factors upon lubricant requirements, elasto-hydrodynamic lubrication, boundary lubrication, machine elements, bio-tribology, metal forming, rheology, lubricated wear and very thin film (nano metre) lubrication. Presented by leading scientists from 22 different countries, these proceedings provide an up-to-date review of developments in this field.

Author : Ramsey Gohar
Publisher : World Scientific
Page : 474 pages
File Size : 46,8 Mb
Release : 2001
Category : Technology & Engineering
ISBN : 1860941702

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Elastohydrodynamics by Ramsey Gohar Pdf

Elastohydrodynamic lubrication (EHL) is a difficult topic, embracing several disciplines, which can cause many problems for engineers and scientists. This up-to-date volume explains the subject both theoretically and experimentally. Moreover, with a refreshing approach and using several novel techniques of application, it provides lucid coverage of new and important findings. Here, in one volume, are the results of much research over the last forty years. The author's clear explanation of the theory of EHL is authoritatively applied to a wide range of related topics, with physical explanations wherever possible. Many of the experimental techniques described were carried out at the Imperial College Lubrication Laboratory, where the application of interferometry (a means of measuring the EHL film thickness) was pioneered.

Author : Charles W. Allen,Dennis P. Townsend,Erwin V. Zaretsky
Publisher : Unknown
Page : 36 pages
File Size : 53,8 Mb
Release : 1972
Category : Forces and couples
ISBN : UIUC:30112106954388

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Comparison of Conventional and Microasperity Elastohydrodynamic Lubrication of a Ball Spinning in a Nonconforming Groove by Charles W. Allen,Dennis P. Townsend,Erwin V. Zaretsky Pdf

An analysis was developed for the microasperity elastohydrodynamic lubrication of a ball spinning in a nonconforming groove. This analysis was compared to the conventional elastohydrodynamic analysis of a ball spinning in a nonconforming groove. Rheological models for a di-2-ethylhexyl sebacate, a super-refined naphthenic mineral oil, and a polyphenyl ether (5P4E) were constructed from spinning torque data by using both analyses. The value of the lubricant pressure-viscosity coefficient that makes the data fit the analyses of the fluids differs somewhat from published data. For all three lubricants, an exponential composite model best described the lubricant rheology. Good agreement existed with the experimental and analytical values of torque for both the conventional and microasperity elastohydrodynamic analysis for a spinning ball in a nonconforming groove.

Author : Pei Moo Ku
Publisher : Unknown
Page : 552 pages
File Size : 51,5 Mb
Release : 1973
Category : Government publications
ISBN : UIUC:30112104124141

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Interdisciplinary Approach to Liquid Lubricant Technology by Pei Moo Ku Pdf

The proceedings of a conference of liquid lubricant technology are presented. The subjects discussed are: (1) requirements and functions of liquid lubricants, (2) mineral oils, (3) greases, (4) theory of rheology, (5) mechanics and thermodynamics in lubrication, (6) environmental capability of liquid lubricants, and (7) wear corrosion and erosion.

Author : Wassim Habchi
Publisher : John Wiley & Sons
Page : 464 pages
File Size : 47,7 Mb
Release : 2018-07-23
Category : Technology & Engineering
ISBN : 9781119225126

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Finite Element Modeling of Elastohydrodynamic Lubrication Problems by Wassim Habchi Pdf

Covers the latest developments in modeling elastohydrodynamic lubrication (EHL) problems using the finite element method (FEM) This comprehensive guide introduces readers to a powerful technology being used today in the modeling of elastohydrodynamic lubrication (EHL) problems. It provides a general framework based on the finite element method (FEM) for dealing with multi-physical problems of complex nature (such as the EHL problem) and is accompanied by a website hosting a user-friendly FEM software for the treatment of EHL problems, based on the methodology described in the book. Finite Element Modeling of Elastohydrodynamic Lubrication Problems begins with an introduction to both the EHL and FEM fields. It then covers Standard FEM modeling of EHL problems, before going over more advanced techniques that employ model order reduction to allow significant savings in computational overhead. Finally, the book looks at applications that show how the developed modeling framework could be used to accurately predict the performance of EHL contacts in terms of lubricant film thickness, pressure build-up and friction coefficients under different configurations. Finite Element Modeling of Elastohydrodynamic Lubrication Problems offers in-depth chapter coverage of Elastohydrodynamic Lubrication and its FEM Modeling, under Isothermal Newtonian and Generalized-Newtonian conditions with the inclusion of Thermal Effects; Standard FEM Modeling; Advanced FEM Modeling, including Model Order Reduction techniques; and Applications, including Pressure, Film Thickness and Friction Predictions, and Coated EHL. This book: Comprehensively covers the latest technology in modeling EHL problems Focuses on the FEM modeling of EHL problems Incorporates advanced techniques based on model order reduction Covers applications of the method to complex EHL problems Accompanied by a website hosting a user-friendly FEM-based EHL software Finite Element Modeling of Elastohydrodynamic Lubrication Problems is an ideal book for researchers and graduate students in the field of Tribology.

Author : Anonim
Publisher : Unknown
Page : 518 pages
File Size : 48,7 Mb
Release : 1976
Category : Electronic
ISBN : MINN:31951000846585L

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NASA Technical Note by Anonim Pdf