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Автор: Grafiati
Опубліковано: 30 травня 2022
Оновлено: 31 травня 2022

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Статті в журналах з теми "Theory of lubrication"

1

Ji, Fen Zhu, Yu Chen Guo, Fa Rong Du, Shu Chun Yang, and Bin Xu. "Research on the Performance of Space Liquid Lubrication System with Oil-Storage." Advanced Materials Research 479-481 (February 2012): 2393–97. http://dx.doi.org/10.4028/www.scientific.net/amr.479-481.2393.

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Анотація:
The gravity oil feed method dose not suit for microgravity environment as the same way dose for ground lubrication system. It is the key problem to be solved that how to supply the oil to friction surface in space liquid lubrication system. It analyzed the lubricating manner. A space liquid lubrication system was designed based on a principle of using deformation energy to supply oil. In the analysis of its basic structure and operating principle, the film calculation mode was established based on the elastohydrodynamic lubrication theory. The lubricating performance was simulated by ANSYS finite element analysis software in microgravity. The calculation results show that: in the microgravity, it could achieve elastohydrodynamic lubrication on friction surface in this lubrication system. When the oil supply hole diameter is 2mm, the film-thickness ratio changes between 1.91 and 4.28. It belongs to elastohydrodynamic lubrication. The hole diameter decreases, the film thickness reduces. The minimum film-thickness ratio is 0.93 when the temperature changes widely from -50°C~+80°C. It belongs to boundary lubrication state.
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2

Scaraggi, M., and B. N. J. Persson. "Theory of viscoelastic lubrication." Tribology International 72 (April 2014): 118–30. http://dx.doi.org/10.1016/j.triboint.2013.12.011.

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3

Zhang, Feng, Gong Bo Han, and Su Xia Duan. "Paper Machine Bearing’s Temperature and Air-Velocity Optimization under Air-Oil Lubrication." Advanced Materials Research 550-553 (July 2012): 3054–58. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.3054.

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Анотація:
The purpose of this resarch was investigated the air-oil temperature field distribution under air-oil lubrication and oil lublubrication, meanwhile also study the air-oil lubrication effect under different air velocity inlet the bearing cavities of the high-speed paper machine dryer section. Base on the CFD theory, the temperature field of CARB bearing outer ring and the velocity field of the bearing cavities were simulated by the FLUENT software.Result show that air-oil lubricatin can reach the same cooling effect is contras with oil lubrication in the same heat production by roller; the best air-velocity value of air-oil lubrication system is obtain for the change of temperature and pressure in bearing cavities. It is confirm that the air-oil lubrication is viable in the high-speed paper machine dryer section.
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4

Olver, A. V. "Gear lubrication—a review." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 216, no. 5 (May 1, 2002): 255–67. http://dx.doi.org/10.1243/135065002760364804.

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Анотація:
The lubrication of gear teeth is reviewed including some key aspects of recent theoretical research and current practice. A simple estimate of the thickness of the lubricating film in a typical pair of spur gears is presented on the basis of classical smooth-body isothermal, elastohydrodynamic lubrication theory. The deficiencies of this simple calculation are then discussed; these include roughness, friction, churning, starvation and contamination, all common features of practical gearing. Three simple methods are described for estimating the tooth temperature and its consequent effect on film thickness.
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5

Zhang, Sheng Fang, Jian Xiu Su, Jia Xi Du, and Ren Ke Kang. "Analysis on Contact Forms of Interface in Wafer CMP Based on Lubricating Behavior." Materials Science Forum 704-705 (December 2011): 313–17. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.313.

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Анотація:
Chemical mechanical polishing (CMP) has become the most widely used planarization technology in the semiconductor manufacturing process. In this paper, the distinguish method of lubricating behavior in wafer CMP had been analyzed in theory firstly. Then, the tests of wafer CMP with silicon wafer and deposited copper wafer at different polishing pressure had been done. By the test results, the Stribeck curves obtained showed obvious smooth. But in normal wafer CMP conditions, the friction coefficient of polishing area was above 0.1. By analyzing the experimental results, it was concluded that the lubrication state in CMP interface is belong to the boundary lubrication and the material removal is the process of bringing and removed of the chemical reaction boundary lubricating film on wafer surface constantly. The contact form between the Wafer and the polishing pad is the solid-solid contact. These results will provide theoretical guide to further understand the material removal mechanism of in wafer CMP. Keywords: Chemical mechanical polishing, material removal mechanism, lubrication form, boundary lubrication.
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6

Lampaert, Stefan G. E., and Ron A. J. van Ostayen. "Lubrication theory for Bingham plastics." Tribology International 147 (July 2020): 106160. http://dx.doi.org/10.1016/j.triboint.2020.106160.

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7

Jang, J. Y., and M. M. Khonsari. "On the granular lubrication theory." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, no. 2062 (August 26, 2005): 3255–78. http://dx.doi.org/10.1098/rspa.2005.1510.

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Анотація:
The governing equations for the flow of a granular material within the context of the lubrication theory are derived. The resulting analysis gives a generalized Reynolds equation that predicts the pressure generation capacity in a bearing with consideration of side flow. A series of simulations are presented that characterize the three-dimensional flow behaviour of powder in a slider bearing.
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8

Shukla, J. B., and D. Kumar. "A theory for ferromagnetic lubrication." Journal of Magnetism and Magnetic Materials 65, no. 2-3 (March 1987): 375–78. http://dx.doi.org/10.1016/0304-8853(87)90075-8.

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9

Zheleznov, A. G., V. A. Godlevskiy, and O. V. Blinov. "Definition of Forming Processes Microparameters for Epitropic Liquid Crystal Boundary Lubrication Layers." Liquid Crystals and their Application 20, no. 4 (December 29, 2020): 72–77. http://dx.doi.org/10.18083/lcappl.2020.4.72.

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Анотація:
The kinetics theory of ordered boundary lubricating layer formation is presented. The theory contains the description of the formation of boundary lubricating layer from liquid lubricating media containing tribo-active adsorbing component. The expressions for specific forming time and thickness of the boundary lubrication layer in the conditions of the considered model are defined. The prospects of the mentioned parameters experimental definition they are marked out. The tribological efficiency parameter of tribological additive is introduced. This parameter can be evaluated in model physicochemical researches or by molecular modelling methods.
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10

Greenwood, James A. "Elastohydrodynamic Lubrication." Lubricants 8, no. 5 (May 6, 2020): 51. http://dx.doi.org/10.3390/lubricants8050051.

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Анотація:
The development of EHL theory from its tentative beginnings is outlined, with an account of how Ertel explained its relation to Hertz contact theory. The problems caused by the failure of the early numerical analysts to understand that the film thickness depends on only two variables are emphasised, and answers of the form H = F ( P , S ) given. Early methods of measuring the film thickness are described, but these became archaic with the development of optical EHL. The behaviour of surface roughness as it passes through the high pressure region and suffers elastic deformation is described, and the implication for the traditional Λ -ratio noted. In contrast, the understanding of traction is far from satisfactory. The oil in the high pressure region must become non-Newtonian: the early explanation that the viscosity reduction is the effect of temperature proved inadequate. There must be some form of shear thinning (perhaps according to the Eyring theory), but also a limiting shear stress under which the lubricant shears as an elastic solid. It seems that detailed, and difficult, measurements of the high pressure, high shear-rate behaviour of individual oils are needed before traction curves can be predicted.
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Більше джерел

Дисертації з теми "Theory of lubrication"

1

Tsandzana, Afonso Fernando. "Homogenization with applications in lubrication theory." Licentiate thesis, Luleå tekniska universitet, Matematiska vetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18727.

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Анотація:
In this licentiate thesis we study some mathematical problems in hydrodynamic lubrication theory. It is composed of two papers (A and B) and a complementary appendix. Lubrication theory is devoted to fluid flow in thin domains. The main purpose of lubrication is to reduce friction and wear between two solid surfaces in relative motion. The mathematical foundations of lubrication theory is given by the Navier--Stokes equation which describes the motion of viscous fluids. In thin domains several approximations are possible which leads to the so called Reynolds equation. This equation is crucial to describe the pressure in the lubricant film. When the pressure is found it is possible to predict different important physical quantities such as friction (stresses on the bounding surfaces), load carrying capacity and velocity field.In many practical situations the surface roughness amplitude and the film thickness are of the same order. Therefore, any realistic model should account for the effect of surface roughness. This implies that the mathematical modelling leads to partial differential equations with coefficients that will oscillate rapidly in space and time due to the relative motion of the surfaces. A direct numerical analysis is very difficult since an extremely fine mesh is required to describe the different scales. One method which has proved successful to handle such problems is to do some averaging (asymptotic analysis). The branch in mathematics which has been developed for this purpose is called homogenization.In Paper A the connection between the Stokes equation and the Reynolds equation is investigated. More precisely, the asymptotic behavior as both the film thickness ε and wavelength μ of the roughness tend to zero is analyzed and described. The results are obtained using the formal method of multiple scale expansion. The limit equation depends on how fast the two small parameters ε and μ go to zero relative to each other. Three different limit equations are derived. Time-dependent equations of Reynolds type are obtained in all three cases (Stokes roughness, Reynolds roughness and high frequency roughness regime).In paper B we present a mathematical model in hydrodynamic lubrication that takes into account cavitation (formation of air bubbles), surface roughness and compressibility of the fluid. We compute the homogenized coefficients in the case of unidirectional roughness. A one-dimensional problem describing a step bearing is also solved explicitly and by numerical methods.

Godkänd; 2014; 20140415 (afotsa); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Afonso Fernando Tsandzana Ämne: Matematik/Mathematics Uppsats: Homogenization with Applications in Lubrication Theory Examinator: Professor Peter Wall, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Professor Anders Holmbom, Mittuniversitetet, Östersund Tid: Onsdag den 11 juni 2014 kl 10.00 Plats: E231, Luleå tekniska universitet

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2

Chien, Ssu-Ying. "Compressible Lubrication Theory in Pressurized Gases." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/88868.

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Анотація:
Lubrication theory plays a fundamental role in all mechanical design as well as applications to biomechanics. All machinery are composed of moving parts which must be protected against wear and damage. Without effective lubrication, maintenance cycles will be shortened to impractical levels resulting in increased costs and decreased reliability. The focus of the work presented here is on the lubrication of rotating machinery found in advanced power systems and designs involving micro-turbines. One of the earliest studies of lubrication is due to Osborne Reynolds in 1886 who recorded what is now regarded as the canonical equation governing all lubrication problems; this equation and its extensions have become known as the Reynolds equation. In the past century, Reynolds equation has been extended to include three-dimensional effects, unsteadiness, turbulence, variable material properties, non-newtonian fluids, multi-phase flows, wall slip, and thermal effects. The bulk of these studies have focused on highly viscous liquids, e.g., oils. In recent years there has been increasing interest in power systems using new working fluids, micro-turbines and non-fossil fuel heat sources. In many cases, the design of these systems employs the use of gases rather than liquids. The advantage of gases over liquids include the reduction of weight, the reduction of adverse effects due to fouling, and compatibility with power system working fluids. Most treatments of gas lubrication are based on the ideal, i.e., low pressure, gas theory and straightforward retro-fitting of the theory of liquid lubrication. However, the 21st Century has seen interest in gas lubrication at high pressures. At pressures and temperatures corresponding to the dense and supercritical gas regime, there is a strong dependence on gas properties and even singular behavior of fundamental transport properties. Simple extrapolations of the intuition and analyses of the ideal gas or liquid phase theory are no longer possible. The goal of this dissertation is to establish the correct form of the Reynolds equation valid for both low and high pressure gases and to explore the dynamics predicted by this new form of the Reynolds equation. The dissertation addresses five problems involving our new Reynolds equation. In the first, we establish the form appropriate for the simple benchmark problem of two-dimensional journal bearings. It is found that the material response is completely determined by a single thermodynamic parameter referred to as the "effective bulk modulus". The validity of our new Reynolds equation has been established using solutions to the full Navier-Stokes-Fourier equations. We have also provided analytical estimates for the range of validity of this Reynolds equation and provided a systematic derivation of the energy equation valid whenever the Reynolds equation holds. The next three problems considered here derive local and global results of interest in high speed lubrication studies. The results are based on a perturbation analysis of our Reynolds and energy equation resulting in simplified formulas and the explicit dependence of pressure, temperature, friction losses, load capacity, and heat transfer on the thermodynamic state and material properties. Our last problem examines high pressure gas lubrication in thrust bearings. We again derive the appropriate form of the Reynolds and energy equations for these intrinsically three-dimensional flows. A finite difference scheme is employed to solve the resultant (elliptic) Reynolds equation for both moderate and high-speed flows. This Reynolds equation is then solved using perturbation methods for high-speed flows. It is found that the flow structure is comprised of five boundary layer regions in addition to the main ``core'' region. The flow in two of these boundary layer regions is governed by a nonlinear heat equation and the flow in three of these boundary layers is governed by nonlinear relaxation equations. Finite difference schemes are employed to obtain detailed solutions in the boundary layers. A composite solution is developed which provides a single solution describing the flow in all six regions to the same accuracy as the individual solutions in their respective regions of validity. Overall, the key contributions are the establishment of the appropriate forms of the Reynolds equation for dense and supercritical flows, analytical solutions for quantities of practical interest, demonstrations of the roles played by various thermodynamic functions, the first detailed discussions of the physics of lubrication in dense and supercritical flows, and the discovery of boundary layer structures in flows associated with thrust bearings.
Doctor of Philosophy
Lubrication theory plays a fundamental role in all mechanical design as well as applications to biomechanics. All machinery are composed of moving parts which must be protected against wear and damage. Without eective lubrication, maintenance cycles will be shortened to impractical levels resulting in increased costs and decreased reliability. The focus of the work presented here is on the lubrication of rotating machinery found in advanced power systems and designs involving micro-turbines. One of the earliest studies of lubrication is due to Osborne Reynolds in 1886 who recorded what is now regarded as the canonical equation governing all lubrication problems; this equation and its extensions have become known as the Reynolds equation. In the past century, Reynolds equation has been extended to include three-dimensional eects, unsteadiness, turbulence, variable material properties, non-newtonian uids, multi-phase ows, wall slip, and thermal eects. The bulk of these studies have focused on highly viscous liquids, e.g., oils. In recent years there has been increasing interest in power systems using new working uids, micro-turbines and non-fossil fuel heat sources. In many cases, the design of these systems employs the use of gases rather than liquids. The advantage of gases over liquids include the reduction of weight, the reduction of adverse eects due to fouling, and compatibility with power system working uids. Most treatments of gas lubrication are based on the ideal, i.e., low pressure, gas theory and straightforward retro-tting of the theory of liquid lubrication. However, the 21st Century has seen interest in gas lubrication at high pressures. At pressures and temperatures corresponding to the dense and supercritical gas regime, there is a strong dependence on gas properties and even singular behavior of fundamental transport properties. Simple extrapolations of the intuition and analyses of the ideal gas or liquid phase theory are no longer possible. The goal of this dissertation is to establish the correct form of the Reynolds equation valid for both low and high pressure gases and to explore the dynamics predicted by this new form of the Reynolds equation. The dissertation addresses ve problems involving our new Reynolds equation. In the rst, we establish the form appropriate for the simple benchmark problem of two-dimensional journal bearings. It is found that the material response is completely determined by a single thermodynamic parameter referred to as the eective bulk modulus. The validity of our new Reynolds equation has been established using solutions to the full Navier-Stokes-Fourier equations. We have also provided analytical estimates for the range of validity of this Reynolds equation and provided a systematic derivation of the energy equation valid whenever the Reynolds equation holds. The next three problems considered here derive local and global results of interest in high speed lubrication studies. The results are based on a perturbation analysis of our Reynolds and energy equation resulting in simplied formulas and the explicit dependence of pressure, temperature, friction losses, load capacity, and heat transfer on the thermodynamic state and material properties. Our last problem examines high pressure gas lubrication in thrust bearings. We again derive the appropriate form of the Reynolds and energy equations for these intrinsically threedimensional ows. A nite dierence scheme is employed to solve the resultant (elliptic) Reynolds equation for both moderate and high-speed ows. This Reynolds equation is then solved using perturbation methods for high-speed ows. It is found that the ow structure is comprised of ve boundary layer regions in addition to the main core region. The ow in two of these boundary layer regions is governed by a nonlinear heat equation and the ow in three of these boundary layers is governed by nonlinear relaxation equations. Finite dierence schemes are employed to obtain detailed solutions in the boundary layers. A composite solution is developed which provides a single solution describing the ow in all six regions to the same accuracy as the individual solutions in their respective regions of validity. Overall, the key contributions are the establishment of the appropriate forms of the Reynolds equation for dense and supercritical ows, analytical solutions for quantities of practical interest, demonstrations of the roles played by various thermodynamic functions, the rst detailed discussions of the physics of lubrication in dense and supercritical ows, and the discovery of boundary layer structures in ows associated with thrust bearings.
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3

Noronha, Noel John. "Analysis of lubrication groove geometry." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4317.

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Анотація:
Thesis (M.S.) University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 20, 2007) Vita. Includes bibliographical references.
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4

Tsandzana, Afonso Fernando. "Homogenization of some new mathematical models in lubrication theory." Doctoral thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-59629.

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Анотація:
We consider mathematical modeling of thin film flow between two rough surfaces which are in relative motion. For example such flows take place in different kinds of bearings and gears when a lubricant is used to reduce friction and wear between the surfaces. The mathematical foundations of lubrication theory is given by the Navier--Stokes equation, which describes the motion of viscous fluids. In thin domains several approximations are possible which lead to the so called Reynolds equation. This equation is crucial to describe the pressure in the lubricant film. When the pressure is found it is possible to predict vorous important physical quantities such as friction (stresses on the bounding surfaces), load carrying capacity and velocity field. In hydrodynamic lubrication the effect of surface roughness is not negligible, because in practical situations the amplitude of the surface roughness are of the same order as the film thickness. Moreover, a perfectly smooth surface does not exist in reality due to imperfections in the manufacturing process. Therefore, any realistic lubrication model should account for the effects of surface roughness. This implies that the mathematical modeling leads to partial differential equations with coefficients that will oscillate rapidly in space and time. A direct numerical computation is therefore very difficult, since an extremely dense mesh is needed to resolve the oscillations due to the surface roughness. A natural approach is to do some type of averaging. In this PhD thesis we use and develop modern homogenization theory to be able to handle the questions above. Especially, we use, develop and apply the method based on the multiple scale expansions and two-scale convergence. The thesis is based on five papers (A-E), with an appendix to paper A, and an extensive introduction, which puts these publications in a larger context. In Paper A the connection between the Stokes equation and the Reynolds equation is investigated. More precisely, the asymptotic behavior as both the film thickness  and wavelength  of the roughness tend to zero is analyzed and described. Three different limit equations are derived. Time-dependent equations of Reynolds type are obtained in all three cases (Stokes roughness, Reynolds roughness and high frequency roughness regime). In paper C we extend the work done in Paper A where we compare the roughness regimes by numeric computations for the stationary case. In paper B we present a mathematical model that takes into account cavitation, surfaces roughness and compressibility of the fluid. We compute the homogenized coefficients in the case of unidirectional roughness.In the paper D we derive a mathematical model of thin film flow between two close rough surfaces, which takes into account cavitation, surface roughness and pressure dependent density. Moreover, we use two-scale convergence to homogenize the model. Finally, in paper E we prove the existence of solutions to a frequently used mathematical model of thin film flow, which takes cavitation into account.
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5

Bryant, Benjamin. "Modeling Moving Droplets: A Precursor Film Approach." Scholarship @ Claremont, 2003. https://scholarship.claremont.edu/hmc_theses/142.

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We investigate the behavior of moving droplets and rivulets, driven by a combination of gravity and surface shear (wind). The problem is motivated by a desire to model the behavior of raindrops on aircraft wings. We begin with the Stokes equations and use the approximations of lubrication theory to derive the specific thin film equation relevant to our situation. This fourth-order partial differential equation describing the height of the fluid is then solved numerically from varying initial conditions, using a fully implicit discretization for time stepping, and a precursor film to avoid singularities at the drop contact line. Results describing general features of droplet deformation, limited parameter studies, and the applicability of our implementation to the long-term goal of modeling wings in rain are discussed.
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6

Campbell, Craig Maurice. "Signature analysis techniques for needle bearing defect detection." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/19539.

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7

Fabricius, John. "Homogenization of some problems in hydrodynamic lubrication involving rough boundaries." Doctoral thesis, Luleå tekniska universitet, Matematiska vetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25734.

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Анотація:
This thesis is devoted to the study of some homogenization problems with applications in lubrication theory. It consists of an introduction, five research papers (I–V) and a complementary appendix.Homogenization is a mathematical theory for studying differential equations with rapidly oscillating coefficients. Many important problems in physics with one or several microscopic scales give rise to this kind of equations, whence the need for methods that enable an efficient treatment of such problems. To this end several mathematical techniques have been devised. The main homogenization method used in this thesis is called multiscale convergence. It is a notion of weak convergence in  Lp spaces which is designed to take oscillations into account. In paper II we extend some previously obtained results in multiscale convergence that enable us to homogenize a nonlinear problem with a finite number of microscopic scales. The main idea in the proof is closely related to a decomposition of vector fields due to Hermann Weyl. The Weyl decomposition is further explored in paper III.Lubrication theory is devoted to the study of fluid flows in thin domains. More generally, tribology is the science of bodies in relative motion interacting through a mechanical contact. An important aspect of tribology is to explain the principles of friction, lubrication and wear. The mathematical foundations of lubrication theory are given by the Navier–Stokes equation which describes the motion of a viscous fluid. In thin domains several simplifications are possible, as shown in the introduction of this thesis. The resulting equation is named after Osborne Reynolds and is much simpler to analyze than the Navier--Stokes equation.The Reynolds equation is widely used by engineers today. For extremely thin films, it is well-known that the surface micro-topography is an important factor in hydrodynamic performance. Hence it is important to understand the influence of surface roughness with small characteristic wavelengths upon the solution of the Reynolds equation. Since the 1980s such problems have been increasingly studied by homogenization theory. The idea is to replace the original equation with a homogenized equation where the roughness effects are “averaged out”. One problem consists of finding an algorithm for computing the solution of the homogenized equation. Another problem consists of showing, on introducing the appropriate mathematical definitions, that the homogenized equation is the correct method of averaging. Papers I, II, IV and V investigate the effects of surface roughness by homogenization techniques in various situations of hydrodynamic lubrication. To compare the homogenized solution with the solution of the deterministic Reynolds equation, some numerical examples are also included.
Godkänd; 2011; 20110408 (johfab); DISPUTATION Ämnesområde: Matematik/Mathematics Opponent: Professor Guy Bayada, Institut National des Sciences Appliquées de Lyon (INSA-LYON), Lyon, France, Ordförande: Professor Lars-Erik Persson, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Tisdag den 7 juni 2011, kl 10.00 Plats: D2214/15, Luleå tekniska universitet
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8

Takagi, Daisuke. "Spreading of viscous fluids and granular materials on slopes." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/228707.

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Materials can flow down a slope in a wide range of geophysical and industrial contexts, including lava flows on volcanoes and thin films on coated surfaces. The aim of my research is to provide quantitative insight into these forms of motion and their dependence on effects of the topography, the volume and the rheology of the flowing structure. Numerous different problems are investigated through mathematical models, which are developed analytically and confirmed by laboratory experiments. The initial advance of long lava flows is studied by considering the flow of viscous fluid released on sloping channels. A scaling analysis, in agreement with analog experiments and field data, offers a practical tool for predicting the advance of lava flows and conducting hazard analysis. A simple and powerful theory predicts the structure of flows resulting from any time-dependent release of fluid down a slope. Results obtained by the method of characteristics reveal how the speed of the advancing front depends importantly on the rate of fluid supplied at an earlier time. Viscous flows on surfaces with different shapes are described by similarity solutions to address problems motivated by engineering as well as geophysical applications. Pouring viscous fluid out of a container can be a frustratingly slow process depending on the shape and the degree of tipping of the container. The discharge rate of the fluid is analysed in simple cases, shedding light on how containers can be emptied most quickly in cosmetic and food industries. In a separate study motivated by coating industries, thin films are shown to evolve with uniform thickness as they drain near the top of a horizontal cylinder or sphere. The leading edge eventually splits into rivulets as predicted theoretically and confirmed by experiments. Debris flows can develop levees and trigger avalanches which are studied by considering dense granular flows down a rough inclined plane. Granular materials released down a slope can produce a flowing structure confined by levees or trigger avalanches at regular intervals, depending on the steady rate of supply. The experimental results are discussed using theoretical ideas of shallow granular flows. Finally, materials flowing in long and slender ducts are investigated theoretically to better understand the digestive and urinary systems in biology. The materials are pumped in an elastic tube by translating waves of muscular contraction and relaxation. The deformation of the tube is predicted by solving a free-boundary problem, a similar mathematical exercise to predicting the moving boundaries of materials spreading on slopes.
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9

Manoylov, Anton. "Modelling of mixed lubrication in plain bearings based on the theory of flow factors and incorporating a dry contact analysis." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/59971/.

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Three topics are considered in this thesis. The first is evaluation of the effective elastic moduli of porous materials and considers materials such as porous glass, sandstone, sintered bronze and iron materials, porous ceramics. Models with spherical pores were first considered showing good agreement for some materials but not for materials prepared by powder sintering. A number of modifications of increasing complexity were introduced accounting for non-spherical pores and their interaction. The models then compare well with experimental data for sintered materials. The other topics of the thesis can be used to model mixed lubrication in plain bearings where part of the load is carried by contacting asperities and part by the lubricant film. The roughness features affect the ability of the lubricant to flow in the gap between the surfaces and surface deflection is caused by asperity contact pressures only. A method is presented to solve dry contact problems for nominally plane surfaces using a simple elastic-plastic model at asperity contacts and a differential formulation for the elastic deflection. Periodic roughness defined over a representative area is incorporated using Fourier transforms to calculate the convolutions. The method is validated by comparison with the results of an elastic-plastic rough surface contact analysis obtained using a finite element method. A method is then developed to model the mixed lubrication problem based on the homogenised Reynolds equation where the effect of the roughness features is isolated from that of the global geometry of the bearing. Local rough problems are solved and the average effect of the roughness on lubricant flow expressed in terms of flow factors, which are functions of global film thickness. When direct asperity contact occurs the deflected shape is obtained from dry contact analysis of the representative roughness area. The global problem is then solved using the Reynolds equation modified with appropriate flow factors taking the mean contact pressure obtained from the local problem into account in load determination. The homogenised method is validated against the series of deterministic solutions and cases of surfaces with measured roughness are presented.
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10

Ulusoy, Suleyman. "The Mathematical Theory of Thin Film Evolution." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16213.

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We try to explain the mathematical theory of thin liquid film evolution. We start with introducing physical processes in which thin film evolution plays an important role. Derivation of the classical thin film equation and existing mathematical theory in the literature are also introduced. To explain the thin film evolution we derive a new family of degenerate parabolic equations. We prove results on existence, uniqueness, long time behavior, regularity and support properties of solutions for this equation. At the end of the thesis we consider the classical thin film Cauchy problem on the whole real line for which we use asymptotic equipartition to show H^1(R) convergence of solutions to the unique self-similar solution.
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Книги з теми "Theory of lubrication"

1

Fluid film lubrication: Theory and design. Cambridge: Cambridge University Press, 1998.

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2

Wierzcholski, Krzysztof. Mathematical methods in hydrodynamic theory of lubrication. Szczecin: Wydawn. Uczelniane Politechniki Szczecińskiej, 1993.

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3

International Tribology Congress. (6th 1993 Budapest, Hungary). EUROTRIB'93: Proceedings : 6th International Congress on Tribology : friction, wear, lubrication, design : theory and practice of tribology, August 30 - September 2, 1993, Budapest, Hungary. [Budapest, Hungary: Hungarian Scientific Society of Mechanical Engineers, 1993.

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4

Reynolds, Osborne. On the theory of lubrication and its application to Mr Beauchamp Tower's experiments, including anexperimental determination of the viscosity of olive oil. London: Institution of Mechanical Engineers, 1986.

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5

Szeri, Andras Z. Fluid Film Lubrication: Theory and Design. Cambridge University Press, 2005.

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6

Booser, E. Richard. Handbook of Lubrication Theory and Design. Society of Tribologists &, 1990.

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7

Booser, E. Richard. CRC Handbook of Lubrication: Theory and Practice of Tribology, Volume II: Theory and Design. CRC, 1988.

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8

Richard, Booser E., ed. CRC handbook of lubrication (theory and practice of triboology). Boca Raton, Florida: CRC Press, 1988.

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9

Totten, George E. Handbook of Lubrication and Tribology: Volume I Application and Maintenance, Second Edition (Handbook of Lubrication (Theory & Practice of Tribology)). 2nd ed. CRC, 2006.

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10

Lubrication and Lubricants: A Treatise on the Theory and Practice of Lubrication, and on the Nature, Properties, and Testing of Lubricants. Franklin Classics, 2018.

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Частини книг з теми "Theory of lubrication"

1

Langlois, William E., and Michel O. Deville. "Lubrication Theory." In Slow Viscous Flow, 229–49. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-03835-3_9.

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2

Qiu, Ming, Long Chen, Yingchun Li, and Jiafei Yan. "Sliding Bearing Lubrication Theory." In Bearing Tribology, 101–43. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-53097-9_5.

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3

Qiu, Ming, Long Chen, Yingchun Li, and Jiafei Yan. "Rolling Bearing Lubrication Theory." In Bearing Tribology, 145–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-53097-9_6.

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4

Wang, Fengcai, and Lynn Niel. "Lubrication Theory for Spherical Bearings." In Encyclopedia of Tribology, 2121–33. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-0-387-92897-5_1197.

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5

Pan, Coda H. "Mathematical Foundation of Fluid Lubrication Theory." In Encyclopedia of Tribology, 2184–95. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-0-387-92897-5_793.

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6

Lugt, P. M., M. T. van Zoelen, and C. H. Venner. "Film Thickness Theory for Single Contacts." In Grease Lubrication in Rolling Bearings, 191–226. Oxford, UK: John Wiley & Sons Ltd, 2012. http://dx.doi.org/10.1002/9781118483961.ch9.

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7

Bresch, Didier, Mathieu Colin, Xi Lin, and Pascal Noble. "Lubrication Theory and Viscous Shallow-Water Equations." In SEMA SIMAI Springer Series, 61–71. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-97613-6_4.

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8

Freitag, Edgar, and Andreas Gropp. "Piston Rod Seal Optimization with the EHD Theory." In Encyclopedia of Lubricants and Lubrication, 1324–31. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-22647-2_343.

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9

Goeleven, D., and R. Oujja. "On Some Mathematical Models Arising in Lubrication Theory." In Applications of Nonlinear Analysis, 355–85. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-89815-5_12.

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10

Lighthill, M. J. "Motion in Narrow Capillaries from the Standpoint of Lubrication Theory." In Ciba Foundation Symposium - Circulatory and Respiratory Mass Transport, 85–104. Chichester, UK: John Wiley & Sons, Ltd., 2008. http://dx.doi.org/10.1002/9780470719671.ch6.

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Тези доповідей конференцій з теми "Theory of lubrication"

1

Li, Wang-Long. "Effects of Electrokinetic Slip Flow on Lubrication Theory." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44167.

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A lubrication theory that includes the effects of electric double layer (EDL) and boundary slip is developed. Both effects are important in microflow, and thus in lubrication problems. They have opposite effects on velocity distributions between lubricating surfaces. Also, the velocity distribution induced by the EDL stream potential (electroviscous effect) is affected by the boundary slip. Under the usual assumptions of lubrication and Debye-Hu¨ckel approximation for low surface potential, the Navier-Stokes equation with body force due to the electrical potential as well as the widely accepted Navier slip boundary conditions is utilized on deriving the modified Reynolds equation. Effects of EDL and boundary slip on the 1-D bearing performance are discussed by solving the modified Reynolds equation numerically.
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2

Tichy, John, Victor Marrero, and Diana-Andra Borca-Tasciuc. "Limits to Lubrication Theory in Microsystems." In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71068.

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Lubrication theory has been one of the most successful and widely used theories in all of engineering and applied science. Therefore, researchers from tribology’s ‘traditional’ wing would be surprised to know that lubrication theory is not at all treated as a given by large group of nontraditional users. In a wide range of conditions applicable to many researchers in microelectromechanical systems (MEMS), experimental results seem to indicate that forces separating surfaces vary according to film thickness to the power minus one, rather than minus three, as lubrication theory requires — a large fundamental discrepancy indeed. Hydrodynamic forces are not generally used to separate surfaces, but arise incidentally, and are usually the largest source of parasitic losses. Clearly, they must be accounted for in the design process.
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3

Lukkassen, Dag, Annette Meidell, and Peter Wall. "On the role of homogenization in lubrication theory." In 10TH INTERNATIONAL CONFERENCE ON MATHEMATICAL PROBLEMS IN ENGINEERING, AEROSPACE AND SCIENCES: ICNPAA 2014. AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4904692.

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4

Kobayashi, Makoto, Takashi Tanabe, Kenshi Ushijima, and Shunichi Aoyama. "A Lubrication Analysis of Multi Link VCR Engine Components using a Mixed Elasto-Hydrodynamic Lubrication Theory Model." In SAE World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2009. http://dx.doi.org/10.4271/2009-01-1062.

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5

Jianping Liu, Qingxuan Jia, Jianping Liu, and Xinyi Zhang. "Theoretical analysis of medical micro-robot using elastohydrodynamic lubrication theory." In 2010 International Conference on Computer Design and Applications (ICCDA 2010). IEEE, 2010. http://dx.doi.org/10.1109/iccda.2010.5541377.

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6

Johansen, Per, Daniel B. Roemer, Henrik C. Pedersen, and Torben O. Andersen. "Analytical Thermal Field Theory Applicable to Oil Hydraulic Fluid Film Lubrication." In ASME/BATH 2014 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fpmc2014-7844.

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An analytical thermal field theory is derived by a perturbation series expansion solution to the energy conservation equation. The theory is valid for small values of the Brinkman number and the modified Peclet number. This condition is sufficiently satisfied for hydraulic oils, whereby the analytical approach provides an alternative to existing computationally expensive numerical methods. The paper presents the dimensional analysis, which provides the foundation for the derivation of the analytical approximation. Subsequently, the perturbation method is applied in order to find an asymptotic expansion of the thermal field. The series solution is truncated at first order in order to obtain a closed form approximation. Finally a numerical thermohydrodynamic simulation of a piston-cylinder interface is presented, and the results are used for a comparison with the analytical theory in order to validate the modelling approach.
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7

Li, Wang-Long. "Effects of Surface Texturing on Lubrication Theory: Consideration of Electrodouble Layer (EDL)." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63241.

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The effects of surface texturing on the electrohydro-dynamic lubrication with thin double layers are considered for the sliding of one charged body past another in an electrolyte solution. The averaged Reynolds type equation as well as the related flow factors is then derived by the flow factor method. The couple effects of surface roughness and EDL appear on flow factors are discussed. The hydrodynamic pressure generated by the viscous force and electrokinetic force are discussed for an 1-D slider bearing.
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8

Jean-Claude, Roux, and Bloch Jean-Francis. "Lubrication theory explains the modification of fiber properties in the refining process." In 11TH INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS 2013: ICNAAM 2013. AIP, 2013. http://dx.doi.org/10.1063/1.4825697.

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9

Mota, Júlia De Araújo, and Juliana Vianna Valério. "Lubrication theory stucly with differentiated geometry parameterization and applications in hydrodynamic bearings." In CNMAC 2021 - XL Congresso Nacional de Matemática Aplicada e Computacional. SBMAC, 2021. http://dx.doi.org/10.5540/03.2021.008.01.0430.

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10

Mora, F., P. Sainsot, A. A. Lubrecht, and Y. le Chenadec. "Lubrication of 2D Soft Elasto Hydrodynamic Contacts: Extension of the Amplitude Reduction Theory." In ASME/STLE 2011 International Joint Tribology Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ijtc2011-61013.

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This paper is an extension of the Amplitude Reduction Theory to soft ElastoHydrodynamic contacts. The ART permits a quantitative prediction of the influence of surface roughness on the lubricant film thickness modification as a function of the operating conditions.
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Звіти організацій з теми "Theory of lubrication"

1

Boettinger, W. J., and G. B. McFadden. Lubrication theory for reactive spreading of a thin drop. Gaithersburg, MD: National Institute of Standards and Technology, 1994. http://dx.doi.org/10.6028/nist.ir.5557.

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2

Lever, James, Austin Lines, Susan Taylor, Garrett Hoch, Emily Asenath-Smith, and Devinder Sodhi. Revisiting mechanics of ice–skate friction : from experiments at a skating rink to a unified hypothesis. Engineer Research and Development Center (U.S.), December 2021. http://dx.doi.org/10.21079/11681/42642.

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The mechanics underlying ice–skate friction remain uncertain despite over a century of study. In the 1930s, the theory of self-lubrication from frictional heat supplanted an earlier hypothesis that pressure melting governed skate friction. More recently, researchers have suggested that a layer of abraded wear particles or the presence of quasi-liquid molecular layers on the surface of ice could account for its slipperiness. Here, we assess the dominant hypotheses proposed to govern ice– skate friction and describe experiments conducted in an indoor skating rink aimed to provide observations to test these hypotheses. Our results indicate that the brittle failure of ice under rapid compression plays a strong role. Our observations did not confirm the presence of full contact water films and are more consistent with the presence of lubricating ice-rich slurries at discontinuous high-pressure zones (HPZs). The presence of ice-rich slurries supporting skates through HPZs merges pressure-melting, abrasion and lubricating films as a unified hypothesis for why skates are so slippery across broad ranges of speeds, temperatures and normal loads. We suggest tribometer experiments to overcome the difficulties of investigating these processes during actual skating trials.
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3

Lever, James, Susan Taylor, Arnold Song, Zoe Courville, Ross Lieblappen, and Jason Weale. The mechanics of snow friction as revealed by micro-scale interface observations. Engineer Research and Development Center (U.S.), December 2021. http://dx.doi.org/10.21079/11681/42761.

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The mechanics of snow friction are central to competitive skiing, safe winter driving and efficient polar sleds. For nearly 80 years, prevailing theory has postulated that self-lubrication accounts for low kinetic friction on snow: dry-contact sliding warms snow grains to the melting point, and further sliding produces meltwater layers that lubricate the interface. We sought to verify that self-lubrication occurs at the grain scale and to quantify the evolution of real contact area to aid modeling. We used high-resolution (15 μm) infrared thermography to observe the warming of stationary snow under a rotating polyethylene slider. Surprisingly, we did not observe melting at contacting snow grains despite low friction values. In some cases, slider shear failed inter-granular bonds and produced widespread snow movement with no persistent contacts to melt (μ < 0.03). When the snow grains did not move and persistent contacts evolved, the slider abraded rather than melted the grains at low resistance (μ < 0.05). Optical microscopy revealed that the abraded particles deposited in air pockets between grains and thereby carried heat away from the interface, a process not included in current models. Overall, our results challenge whether self-lubrication is indeed the dominant mechanism underlying low snow kinetic friction.
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4

Lever, James, Susan Taylor, Garrett Hoch, and Charles Daghlian. Evidence that abrasion can govern snow kinetic friction. Engineer Research and Development Center (U.S.), December 2021. http://dx.doi.org/10.21079/11681/42646.

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The long-accepted theory to explain why snow is slippery postulates self-lubrication: frictional heat from sliding melts and thereby lubricates the contacting snow grains. We recently published micro-scale interface observations that contradicted this explanation: contacting snow grains abraded and did not melt under a polyethylene slider, despite low friction values. Here we provide additional observational and theoretical evidence that abrasion can govern snow kinetic friction. We obtained coordinated infrared, visible-light and scanning-electron micrographs that confirm that the evolving shapes observed during our tribometer tests are contacting snow grains polished by abrasion, and that the wear particles can sinter together and fill the adjacent pore spaces. Furthermore, dry-contact abrasive wear reasonably predicts the evolution of snow-slider contact area and sliding-heat-source theory confirms that contact temperatures would not reach 0°C during our tribometer tests. Importantly, published measurements of interface temperatures also indicate that melting did not occur during field tests on sleds and skis. Although prevailing theory anticipates a transition from dry to lubricated contact along a slider, we suggest that dry-contact abrasion and heat flow can prevent this transition from occurring for snow-friction scenarios of practical interest.
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5

Lever, James, Emily Asenath-Smith, Susan Taylor, and Austin Lines. Assessing the mechanisms thought to govern ice and snow friction and their interplay with substrate brittle behavior. Engineer Research and Development Center (U.S.), December 2021. http://dx.doi.org/10.21079/1168142742.

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Sliding friction on ice and snow is characteristically low at temperatures common on Earth’s surface. This slipperiness underlies efficient sleds, winter sports, and the need for specialized tires. Friction can also play micro-mechanical role affecting ice compressive and crushing strengths. Researchers have proposed several mechanisms thought to govern ice and snow friction, but directly validating the underlying mechanics has been difficult. This may be changing, as instruments capable of micro-scale measurements and imaging are now being brought to bear on friction studies. Nevertheless, given the broad regimes of practical interest (interaction length, temperature, speed, pressure, slider properties, etc.), it may be unrealistic to expect that a single mechanism accounts for why ice and snow are slippery. Because bulk ice, and the ice grains that constitute snow, are solids near their melting point at terrestrial temperatures, most research has focused on whether a lubricating water film forms at the interface with a slider. However, ice is extremely brittle, and dry-contact abrasion and wear at the front of sliders could prevent or delay a transition to lubricated contact. Also, water is a poor lubricant, and lubricating films thick enough to separate surface asperities may not form for many systems of interest. This article aims to assess our knowledge of the mechanics underlying ice and snow friction.
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