scholarly journals Influence of the Heat Transfer Field on Anomalous Lubricant Film Formation in Elastohydrodynamic Lubrication Conditions

2021 ◽  
Vol 69 (3) ◽  
Author(s):  
Kazuyuki Yagi ◽  
Kazuki Nishida ◽  
Joichi Sugimura
Keyword(s):  
Heat Transfer ◽  
Film Formation ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Lubrication Conditions

scholarly journals Influence of the heat transfer field on anomalous lubricant film formation in elastohydrodynamic lubrication conditions

2021 ◽  
Author(s):  
Kazuyuki Yagi ◽  
Kazuki Nishida ◽  
Joichi Suigmura
Keyword(s):  
Heat Transfer ◽  
Phase Diagram ◽  
White Light ◽  
Film Formation ◽  
Friction Pair ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Liquid Lubricant ◽  
Sapphire Disc ◽  
Lubrication Conditions

Abstract The influence of the heat transfer field on anomalous film formation under elastohydrodynamic lubrication (EHL) conditions was studied. Liquid lubricant film shapes between a transparent disc and steel ball friction pair were investigated by white light optical interferometry. 1-Dodecanol was used as the representative lubricant to develop anomalous film shapes. A sapphire disc and glass disc, which have different thermal conductivities, were used as the transparent bounding surface. The heat transfer field significantly influenced the formation of anomalous film shapes. The anomalous film shapes approximated the shape of a conventional EHL film with increasing ambient temperature. However, a thickened part of the lubricant film remained, although the phase diagram of 1-dodecanol suggested it to be in the liquid state.

scholarly journals Nano-lubricant film formation due to combined elastohydrodynamic and surface force action under isothermal conditions

2001 ◽  
Vol 215 (9) ◽  
pp. 1019-1029 ◽  
Author(s):  
M. F. Abd-AlSamieh ◽  
H Rahnejat
Keyword(s):  
Film Formation ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Surface Force ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Numerical Work ◽  
Isothermal Conditions ◽  
Numerical Predictions

This paper presents the results of numerical prediction of the lubricant film thickness and pressure distribution in concentrated counterformal point contact under isothermal conditions. The operating conditions, which include load and speed of entraining motion, promote the formation of ultra-thin films; these are formed under the combined action of elastohydrodynamic lubrication (EHL), the surface contact force of solvation and molecular interactions due to the presence of Van der Waals forces. A numerical solution has been carried out, using the low-relaxation Newton-Raphson iteration technique, applied to the convergence of the hydrodynamic pressure. The paper shows that the effect of surface forces become significant as the elastic film (i.e. the gap) is reduced to a few nanometres. The numerical predictions have been shown to conform well to the numerical work and experimental findings of other research workers.

Film formation in EHL contacts with oil-impregnated sintered materials

2018 ◽  
Vol 70 (4) ◽  
pp. 612-619 ◽  
Author(s):  
Milan Omasta ◽  
Martin Ebner ◽  
Petr Šperka ◽  
Thomas Lohner ◽  
Ivan Krupka ◽  
...  
Keyword(s):  
Film Thickness ◽  
Sintered Material ◽  
Film Formation ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Operating Conditions ◽  
Lubricant Film Thickness ◽  
Content Type ◽  
Film Forming ◽  
Highly Loaded

PurposeThe purpose of this study is to investigate lubricant film-forming capability of oil-impregnated sintered material in highly loaded non-conformal contacts. This self-lubrication mechanism is well described in lightly loaded conformal contacts such as journal bearings; however, only a little has been published about the application to highly loaded contacts under elastohydrodynamic lubrication regime (EHL).Design/methodology/approachThin film colorimetric interferometry is used to describe the effect of different operating conditions on lubricant film formation in line contacts.FindingsUnder fully flooded conditions, the effect of porous structure can be mainly traced back to the different elastic properties. When the contact is lubricated only by oil bleeding from the oil-impregnated sintered material, starvation is likely to occur. It is indicated that lubricant film thickness is mainly governed by oil bleeding capacity. The relationship between oil starvation parameters corresponds well with classic starved EHL theory.Practical implicationsTo show practical, relevant limitations of the considered self-lubrication system, time tests were conducted. The findings indicate that EHL contact with oil-impregnated sintered material may provide about 40 per cent of fully flooded film thickness.Originality/valueFor the first time, the paper presents results on the EHL film-forming capability of oil-impregnated sintered material by measuring the lubricant film thickness directly. The present paper identifies the phenomena involved, which is necessary for the understanding of the behavior of this complex tribological system.

scholarly journals Comparison Between the Action of Nano-Oxides and Conventional EP Additives in Boundary Lubrication

Lubricants ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 54
Author(s):  
Valdicleide Silva Mello ◽  
Marinalva Ferreira Trajano ◽  
Ana Emilia Diniz Silva Guedes ◽  
Salete Martins Alves
Keyword(s):  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Friction And Wear ◽  
Film Formation ◽  
Environmental Issues ◽  
Protective Film ◽  
Extreme Pressure ◽  
Extreme Pressure Additives ◽  
Environmental Requirements ◽  
Lubrication Conditions

Additives are essential in lubricant development, improving their performance by the formation of a protective film, thus reducing friction and wear. Some such additives are extreme pressure additives. However, due to environmental issues, their use has been questioned because their composition includes sulfur, chlorine, and phosphorus. Nanoparticles have been demonstrated to be a suitable substitute for those additives. This paper aims to make a comparison of the tribological performance of conventional EP additives and oxides nanoparticles (copper and zinc) under boundary lubrication conditions. The additives (nanoparticles, ZDDP, and sulfur) were added to mineral and synthetic oils. The lubricant tribological properties were analyzed in the tribometer HFRR (high frequency reciprocating rig), and during the test, the friction coefficient and percentual of film formation were measured. The wear was analyzed by scanning electron microscopy. The results showed that the conventional EP additives have a good performance owing to their anti-wear and small friction coefficient in both lubricant bases. The oxides nanoparticles, when used as additives, can reduce the friction more effectively than conventional additives, and displayed similar behavior to the extreme pressure additives. Thus, the oxide nanoparticles are more environmentally suitable, and they can replace EP additives adapting the lubricant to current environmental requirements.

A Numerical Study on Heat Transfer and Lubricant Depletion on an Anisotropic Multilayer Hard Disk

2012 ◽  
Vol 232 ◽  
pp. 770-774
Author(s):  
Yan Zeng ◽  
Xiao Yang Huang ◽  
Wei Dong Zhou ◽  
Sheng Kai Yu
Keyword(s):  
Heat Transfer ◽  
Laser Power ◽  
Numerical Study ◽  
Disk Surface ◽  
Lubricant Film ◽  
Multilayer Structures ◽  
Lubricant Depletion ◽  
Thermal Anisotropy ◽  
Anisotropy Effect ◽  
Higher Temperature

This paper presents a numerical investigation on the effect of thermal anisotropy of the top layer alloy on heat transfer and lubricant depletion on the disk surface in a heat-assisted magnetic recording (HAMR) system. The disk consists of multilayer structures and a thin layer of lubricant on the top surface. Cases under different laser powers and initial lubricant film thicknesses are examined. The top-layer alloy thermal anisotropy does show non-negligible effect on the heat transfer and lubricant depletion. With the top-layer alloy being more anisotropic, higher temperature increase and lager lubricant depletion can be observed on the disk surface. The results also show that the thermal anisotropy effect is more significant under a lower laser power but nearly keeps no much difference under different initial lubricant film thicknesses. Thus it is of importance to include the thermal anisotropy effect of the top-layer Co-alloy when simulating the heat transfer and lubricant depletion in practical multilayer HMAR systems, especially for the cases under the condition of lower laser power, as the effect cannot be neglected under such conditions.

Quantitative Analysis of Reynolds and Navier–Stokes Based Modeling Approaches for Isothermal Newtonian Elastohydrodynamic Lubrication

2021 ◽  
Vol 143 (12) ◽  
Author(s):  
Leoluca Scurria ◽  
Tommaso Tamarozzi ◽  
Oleg Voronkov ◽  
Dieter Fauconnier
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Thickness Distribution ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Shear Stresses ◽  
Low Viscosity ◽  
Fluid Film Thickness

Abstract When simulating elastohydrodynamic lubrication, two main approaches are usually followed to predict the pressure and fluid film thickness distribution throughout the contact. The conventional approach relies on the Reynolds equation to describe the thin lubricant film, which is coupled to a Boussinesq description of the linear elastic deformation of the solids. A more accurate, yet a time-consuming method is the use of computational fluid dynamics in which the Navier–Stokes equations describe the flow of the thin lubricant film, coupled to a finite element solver for the description of the local contact deformation. This investigation aims at assessing both methods for different lubrication conditions in different elastohydrodynamic lubrication (EHL) regimes and quantify their differences to understand advantages and limitations of both methods. This investigation shows how the results from both approaches deviate for three scenarios: (1) inertial contributions (Re > 1), i.e., thick films, high speed, and low viscosity; (2) high shear stresses leading to secondary flows; and (3) large deformations of the solids leading to inaccuracies of the Boussinesq equation.

Transient Heat Transfer Simulation of the Coupling 3-D Moving Piston Assembly-Lubricant Film-Liner System

2006 ◽  
Author(s):  
Liu Zhien ◽  
Jiang Yankun ◽  
Chen Guohua ◽  
Yang Wanli
Keyword(s):  
Heat Transfer ◽  
Piston Ring ◽  
Cylinder Liner ◽  
Heat Transfer Model ◽  
Lubricant Film ◽  
Transient Heat Transfer ◽  
Transfer Model ◽  
Friction Heat ◽  
Liner System ◽  
Piston Assembly

Transient heat transfer model of the coupling 3-D moving piston assembly-lubricant film-liner system is successfully developed for predicting the temperature distributions in the component system of internal combustion chamber, in which the effect of the friction heat generated at the piston ring/cylinder liner interfaces has been taken into account. The finite element method (FEM) is employed in the model for establishing the heat transfer relation among the moving piston assembly-lubricant film-cylinder liner. The 3-D discrete model of the coupling system is obtained by hypothesizing the lubricant film as 1-D thermal resistances and the friction heat as heat flux boundary conditions. The allocation and distribution model of friction heat on piston ring pack and liner are also established. The 3-D coupling heat transfer model has been used to analyze the heat transfer of a gasoline engine.

Formation of Lubricant Film in Rotary Sealing Contacts: Part II—A New Measuring Principle for Lubricant Film Thickness

1992 ◽  
Vol 114 (2) ◽  
pp. 290-296 ◽  
Author(s):  
G. Poll ◽  
A. Gabelli
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Lip Seal ◽  
Tribological System ◽  
Lip Seals ◽  
Magnetite Particles ◽  
Rotary Speed ◽  
Fluid Film Thickness ◽  
Insight Into

The development of models for the elastohydrodynamic lubrication of rotary lip seals requires the measurement of the film thickness under a real seal. A new method has been developed for this purpose which is based on the use of lubricant oils in which magnetite particles are suspended (so-called magnetic fluids). A change in the fluid film thickness will create a change in the impedance of the coil of the measuring circuit, the magnetic flux of which is directed through the oil film of the contact area. The advantage of this technique is that minimal modifications have to be applied to the tribological system under examination. Initial measurements carried out with a model rubber lip seal provided new insight into the build-up of a lubricant film as a function of the rotary speed and allowed comparison with the results of a theoretical model for the analysis of lip seal lubrication developed in parallel.

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