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Author: B.O. Jacobson Publisher: Elsevier ISBN: 0080875831 Category : Science Languages : en Pages : 399
Book Description
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: B.O. Jacobson Publisher: Elsevier ISBN: 0080875831 Category : Science Languages : en Pages : 399
Book Description
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 ISBN: 0080475302 Category : Technology & Engineering Languages : en Pages : 262
Book Description
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: Edward G. Trachman Publisher: ISBN: Category : Fluid-film bearings Languages : en Pages : 220
Book Description
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: D. Dowson Publisher: Elsevier ISBN: 1483181898 Category : Technology & Engineering Languages : en Pages : 254
Book Description
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: Ramsey Gohar Publisher: World Scientific ISBN: 1786345196 Category : Technology & Engineering Languages : en Pages : 519
Book Description
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: Ramsey Gohar Publisher: World Scientific ISBN: 9781860941702 Category : Technology & Engineering Languages : en Pages : 474
Book Description
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: B.O. Jacobson
Author: B.O. Jacobson
Author: Alan Dyson
Author: Scott S. Bair
Author: Edward G. Trachman
Author: D. Dowson
Author: Ramsey Gohar
Author: R. K. Kunz
Author: Bernard J. Hamrock
Author: Ramsey Gohar
Author: