Download or read book Friction in Mixed and Elastohydrodynamic Lubricated Contacts Including Thermal Effects written by Qiang Liu and published by . This book was released on 2002 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Elasto Hydrodynamic Lubrication written by D. Dowson and published by Elsevier. This book was released on 2014-07-18 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Interfacial Mechanics written by Jane Wang and published by CRC Press. This book was released on 2019-12-06 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the characteristics of material contact and lubrication at tribological interfaces is of great importance to engineering researchers and machine designers. Traditionally, contact and lubrication are separately studied due to technical difficulties, although they often coexist in reality and they are actually on the same physical ground. Fast research advancements in recent years have enabled the development and application of unified models and numerical approaches to simulate contact and lubrication, merging their studies into the domain of Interfacial Mechanics. This book provides updated information based on recent research progresses in related areas, which includes new concepts, theories, methods, and results for contact and lubrication problems involving elastic or inelastic materials, homogeneous or inhomogeneous contacting bodies, using stochastic or deterministic models for dealing with rough surfaces. It also contains unified models and numerical methods for mixed lubrication studies, analyses of interfacial frictional and thermal behaviors, as well as theories for studying the effects of multiple fields on interfacial characteristics. The book intends to reflect the recent trends of research by focusing on numerical simulation and problem solving techniques for practical interfaces of engineered surfaces and materials. This book is written primarily for graduate and senior undergraduate students, engineers, and researchers in the fields of tribology, lubrication, surface engineering, materials science and engineering, and mechanical engineering.

Download or read book Thermal Elastohydrodynamic Lubrication of Line Contacts written by and published by . This book was released on 1983 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rheological Effects on Friction in Elastohydrodynamic Lubrication written by Edward G. Trachman and published by . This book was released on 1973 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Encyclopedia of Tribology written by Q. Jane Wang and published by Springer. This book was released on 2013-09-26 with total page 4139 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRIBOLOGY – the study of friction, wear and lubrication – impacts almost every aspect of our daily lives. The Springer Encyclopedia of Tribology is an authoritative and comprehensive reference covering all major aspects of the science and engineering of tribology that are relevant to researchers across all engineering industries and related scientific disciplines. This is the first major reference that brings together the science, engineering and technological aspects of tribology of this breadth and scope in a single work. Developed and written by leading experts in the field, the Springer Encyclopedia of Tribology covers the fundamentals as well as advanced applications across material types, different length and time scales, and encompassing various engineering applications and technologies. Exciting new areas such as nanotribology, tribochemistry and biotribology have also been included. As a six-volume set, the Springer Encyclopedia of Tribology comprises 1630 entries written by authoritative experts in each subject area, under the guidance of an international panel of key researchers from academia, national laboratories and industry. With alphabetically-arranged entries, concept diagrams and cross-linking features, this comprehensive work provides easy access to essential information for both researchers and practicing engineers in the fields of engineering (aerospace, automotive, biomedical, chemical, electrical, and mechanical) as well as materials science, physics, and chemistry.

Download or read book IUTAM Symposium on Elastohydrodynamics and Micro elastohydrodynamics written by R.W. Snidle and published by Springer Science & Business Media. This book was released on 2006-01-09 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of the IUTAM Symposium on Elastohydrodynamics and Microelastohydrodynamics held in Cardiff from 1-3 September 2004. It contains 31 articles by leading researchers in the field. The symposium focused on theoretical, experimental and computational issues in elastohydrodynamic lubrication (EHL) both in relation to smooth surfaces and in situations where the film is of the same order or thinner than the surface roughness (micro-EHL). The last IUTAM Symposium in this general area of contact of deformable bodies was in 1974. The emphasis in the Symposium was upon fundamental issues such as: solution methods; lubricant rheological models, thermal effects; both low and high elastic modulus situations; human and replacement joints; fluid traction; dynamic effects, asperity lubrication and the failure of lubrication; surface fatigue and thermal distress under EHL conditions. The book will be useful to those active in basic elastohydrodynamics research who wish to gain an up-to-date understanding of the subject from leading experts in the field.

Download or read book Thermal Elastohydrodynamic Lubrication of Rolling sliding Contacts written by Farshid Sadeghi and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A complete numerical solution of thermal compressible elastohydrodynamic lubrication of rolling/sliding contacts has been obtained. The Newton-Raphson technique is used to solve the simultaneous system of Reynolds and elasticity equations. The control volume finite element modeling was employed to solve the energy equation and its boundary conditions. The effects of various loads, speeds, and slip conditions on the lubricant temperature, film thickness, and friction force have been investigated. The results indicate that the temperature effects are significant and cannot be neglected.

Download or read book Fundamentals of Fluid Film Lubrication written by Bernard J. Hamrock and published by CRC Press. This book was released on 2004-03-15 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt: Specifically focusing on fluid film, hydrodynamic, and elastohydrodynamic lubrication, this edition studies the most important principles of fluid film lubrication for the correct design of bearings, gears, and rolling operations, and for the prevention of friction and wear in engineering designs. It explains various theories, procedures, and equations for improved solutions to machining challenges. Providing more than 1120 display equations and an introductory section in each chapter, Fundamentals of Fluid Film Lubrication, Second Edition facilitates the analysis of any machine element that uses fluid film lubrication and strengthens understanding of critical design concepts.

Download or read book Boundary and Mixed Lubrication Science and Applications written by D. Dowson and published by . This book was released on 2002-07-10 with total page 694 pages. Available in PDF, EPUB and Kindle. Book excerpt: Session headings. Keynote address and invited paper. Boundary lubrication 1. Boundary lubrication 2. Mixed lubrication. Lubricants 1. Lubricants 2. Nano-boundary lubrication and molecular dynamics. Coatings. Dry wear. Lubricated wear. Bio-tribology- total replacement hip joints. Elastohydrodynamic lubrication. Friction 1. Bearings. Friction 2. Mechanical systems.

Download or read book Assessment of Lubricated Contacts Mechanisms of Scuffing and Scoring written by and published by . This book was released on 1983 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lubrication at the Frontier The Role of the Interface and Surface Layers in the Thin Film and Boundary Regime written by M. Priest and published by Elsevier. This book was released on 1999-07-01 with total page 911 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 25th Leeds-Lyon Symposium on Tribology was held at the Institut des Sciences Appliquées de Lyon, from 8-11th September, 1998. Its central theme was, "Lubrication at the frontier: the role of the interface and surface layers in the thin film and boundary regime". This topic was chosen because it represents an important evolution of the research field.The Symposium opened with a keynote address entitled "Role of surface-anchored polymer chains in polymer friction" which described the processes taking place at the interface between "solid" and "liquid". The keynote address was followed by two invited lectures. Firstly, "Fuel efficient engine oils, additive interactions, boundary friction and wear" presented the industrial point of view on lubricant formulation and engine testing and its evolution. The second lecture was entitled "For establishment of a new EHL theory" and stressed the need to extend the current EHL theory.Beginning in 1974, The Leeds-Lyon Symposia have now covered a wide range of topics. The essential aim each year is to select a topic of current interest to tribologists and to contribute to further the advance of knowledge in selected fields.

Download or read book Effects of Lubrication Starvation on Flash Temperature for Thermal Mixed Elastohydrodynamic Gear Contacts written by Danielle D. Massé and published by . This book was released on 2019 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lubrication is provided to the gear trains in automotive and aerospace transmission systems to prevent mechanical contact through the formation of a full lubricant film, which in turn removes heat generated at the gear contact surfaces. When debris blocks the inlet nozzle, the flow of lubricant is restricted and mechanical components experience lubrication starvation. Under starved lubrication the temperatures of the contact surfaces become elevated which can lead to the formation of a weld between them, a catastrophic failure mode called scuffing. For spur gears, the occurrence of scuffing is due to high sliding in the vicinity of the root or tip, where the shear thinning effect decreases the lubrication film thickness. This lubricant depletion increases the contact pressure and frictional heat flux beyond a critical limit, resulting in weld formation. The weld is immediately torn apart by the continuous relative motion of the components, causing extreme damage to the tooth surfaces. The objective of this study is to characterize the tribological behavior of high sliding gear contacts under starved lubrication. This is achieved through numerical flow simulations which utilize a generalized Reynolds equation with a non-Newtonian flow coefficient, and incorporate the dependence of lubricant viscosity on pressure and temperature. In order to study the effects of lubrication starvation a film fraction parameter is used in the Reynolds equation, removing the need for measured or assumed inlet lubrication geometry. This work presents a parametric study of engineering surface profiles under different operating conditions to show an asymptotic relationship between flash temperature and the severity of the lubrication starvation, supported by an analysis of pressure, film fraction parameter, friction coefficient, and power loss. The results of these investigations justify further numerical and experimental studies of scuffing failure for gear contacts.

Download or read book Grease Lubrication in Rolling Bearings written by Piet M. Lugt and published by John Wiley & Sons. This book was released on 2012-12-10 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: The definitive book on the science of grease lubrication for roller and needle bearings in industrial and vehicle engineering. Grease Lubrication in Rolling Bearings provides an overview of the existing knowledge on the various aspects of grease lubrication (including lubrication systems) and the state of the art models that exist today. The book reviews the physical and chemical aspects of grease lubrication, primarily directed towards lubrication of rolling bearings. The first part of the book covers grease composition, properties and rheology, including thermal and dynamics properties. Later chapters cover the dynamics of greased bearings, including grease life, bearing life, reliability and testing. The final chapter covers lubrications systems – the systems that deliver grease to the components requiring lubrication. Grease Lubrication in Rolling Bearings: Describes the underlying physical and chemical properties of grease. Discusses the effect of load, speed, temperature, bearing geometry, bearing materials and grease type on bearing wear. Covers both bearing and grease performance, including thermo-mechanical ageing and testing methodologies. It is intended for researchers and engineers in the petro-chemical and bearing industry, industries related to this (e.g. wind turbine industry, automotive industry) and for application engineers. It will also be of interest for teaching in post-graduate courses.

Download or read book Investigation of Dynamic Friction in Lubricated Surfaces written by Hanuman Rachoor and published by . This book was released on 1995 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research reported in this dissertation is concerned with the development of friction models for lubricated contacts. A few analytical models have been developed to investigate the friction under dynamic velocity conditions. In this study, two different tribological situations such as conformal and non-conformal contacts have been chosen. Friction modeling covers boundary, mixed and full fluid film friction regions. A new theory based on the elastic properties of the surface materials, and fluid film properties of the lubricant at the contact has been developed to determine the dynamic friction in boundary, mixed and full hydrodynamic lubrication regions. In the full fluid film lubrication region, friction has been determined from the lubrication principles based on the tribological situation, i.e., hydrodynamic lubrication theory for a short journal bearing and elastohydrodynarnic lubrication theory for a line contact. A conformal contact formed by a short journal bearing operating in the region where hydrodynamic lubrication theory is valid has been considered to develop a model. The model is simulated for unidirectional as well as bi-directional sinusoidal velocity oscillations for various frequencies. Simulation resulted in a phase lag in the fiction and hysteresis in ftiction versus velocity (f vs. U) curves. The results obtained for unidirectional velocity oscillations indicate qualitative agreement with experimental work on lubricated line contact by Hess and Soom (1990). Results for bi-directional oscillations also show phase lag in friction and similar hysteresis in f vs U curves. In addition to the hysteresis, results for the bi-directional velocity oscillations show a discontinuity in friction at velocity reversals. These results have been verified experimentally. A special apparatus to measure the friction has been designed and built by using a sleeve bearing. Experiments have been conducted to measure friction under various velocity conditions, and the results have been used to determine the coefficients required to simulate the analytical model. The analytical model has been simulated for the above coefficients and the results have been compared with the friction measurements. The comparison shows similar hysteresis in f vs U curves for uni-directional and bi-directional velocity oscillations. However, the friction behavior of the apparatus during bi-directional oscillations differs in the magnitude of the discontinuity (step function) at velocity reversals. The above analytical friction model developed for the hydrodynamic short journal bearing has been extended to investigate the effect of resisting forces on the dynamic friction behavior at low speed. Resistance forces include sliding friction as well as the presliding friction Dahl effect. The Dahl effect is due to elastic deformation of the compliance in the system before the force reaches the breakaway magnitude when sliding initiates. In this study, stiffness of the asperities as well as elastic support have been considered. Simulation results of the model for uni-directional velocity oscillations are in qualitative agreement with earlier experimental work. Simulation of the model for bi-directional velocity oscillations shows that the discontinuity at velocity reversals has been replaced by a line with slope. This work indicates that the stiffness, of the elastic compliance can play a significant role in replacing the discontinuity. The above concepts of friction modeling has been extended for a non-conformal contact formed with a cylindrical surface sliding over a flat surface operating on elastohydrodynamic lubrication theory. In this model, elastohydrodynamic lubrication theory has been used to determine the friction in full fluid film region. Simulation results of this model for uni-directional as well as bi-directional sinusoidal velocity oscillations indicate a similar phase lag in the friction and hysteresis in f vs. U curves as observed in the earlier models. Results of the present investigation indicate that the instantaneous friction is not only a function of the instantaneous velocity, but it is also a function of previous velocity or velocity history. These models can be improved with the aid of more experimental work. Also, these models can be extended for stick-slip analysis and for friction compensation.

Download or read book Surface Roughness Effects in Hydrodynamic and Mixed Lubrication written by Steve M. Rohde and published by . This book was released on 1980 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Theoretical and experimental results on friction for line contacts in mixed and elastohydrodynamic lubrication regimes written by Roberto Bassani and published by . This book was released on 1999 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: