2 edition of Conditions for the rupture of a lubricating film found in the catalog.
Conditions for the rupture of a lubricating film
James C. Coyne
in [New York]
Written in English
|Statement||[by] James C. Coyne.|
|LC Classifications||TJ1073.5 .C66|
|The Physical Object|
|Pagination||viii, 69, v, 75 l.|
|Number of Pages||75|
|LC Control Number||70010146|
where μ and ρ are the viscosity and density of the lubricant. A generalization of this thin film approximation which considers the effects of non-Newtonian fluids can e.g. be found in the Encyclopaedia of Tribology, see the entry  by Larsson.. A fluid cannot sustain large tensile stress and it is known that when the pressure becomes too low the continuous film will rupture and air bubbles. Cavitation Phenomena and Numerical Analysis. Cite this entry as: () Lubricant Film Rupture. In: Wang Q.J., Chung YW.
G. Li, Study on film-forming mechanisms and tribological properties of grease in the harsh conditions, Ph. D. thesis, Tsinghua University, Beijing, Google Scholar S.H. Liu, Studies on lubricating mechanisms and tribological properties of aqueous solutions, Ph. D. thesis, Tsinghua University, Beijing, Google Scholar. The thickness of this film has been measured by a capacitance method up to loads of Lb. per inch of face (1\cdot 76 × dyn cm-1) for conditions of pure rolling and for conditions of.
About this book. Praise for the previous edition: “Contains something for everyone involved in lubricant technology” — Chemistry & Industry. This completely revised third edition incorporates the latest data available and reflects the knowledge of one of the largest companies active in the business. The authors take into account the. Most dry lubrication film materials work well in dry environments and are excellent supplemental or boundary layer materials in fluid systems. 1 The long chain fluorocarbon molecules, such as polytetrafluoroethylene, tend to have wetting angles that promote release and prevent sticking, as well as a variety of other attractive characteristics.
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A companion article has been published: Conditions for the Rupture of a Lubricating Film—Part II: New Boundary Conditions for Reynolds Equation A commentary has been published: Closure to “Discussion of ‘The Use of Model Materials in Predicting Forming Loads in Metalworking’” (, ASME J.
Eng. Ind., 92, pp. –)Cited by: The pressure and flow conditions upstream of the rupture point of a lubricating film are analyzed with the theoretical model derived in Part I.
The boundary conditions on the pressure and pressure gradient for use with Reynolds’ equation are developed as functions of a dimensionless parameter involving viscosity, speed, and surface by: When the ambient conditions are such that no lubricant film rupture takes place, then the bearing behaviour is changed.
For the 4 pad configuration treated in one can note that : a) operating an unloaded bearing becomes impossible when geometrical preload m is higher than b). Highlights Boundary conditions for Reynolds equation are discussed in a systematic fashion.
Rupture location in the Cameron-Wood solution is linear to eccentricity ratio. With given eccentricity and inlet position, inlet pressure ties to flow rate.
For a dimpled step bearing, intermediate film thickness triggers by: 4. On the Appearance of Lubricant Film Rupture in Cylindrical Journal Bearings. Tribology Transactions: Vol. 47, No. 2, pp. The lubricant film thickness computed by the Hamrock and Dowson's formulae (14) and corrected by the Gupta, Cheng and al.'s coefficient (15) to account for the thermal effects is equal to μm.
The different particle sizes used range up to μm. So it is not surprising if the particles are strongly deformed or broken up when they are entrapped in the inlet or during their transit.
A simplified boundary condition at film rupture proposed by Ota () was employed. The theory was extended to investigate the wave number of the film rupture surface and to investigate the effect of gas bubbles included in the lubricant.
Lubricant film rupture is considered through application of incipient reverse flow boundary condition, which is representative of lubricant film separation. The results point to the operating conditions at which significant power losses occur.
The boundary conditions for the modified Reynolds separation condition are at x =x, p =p2, -=O dP dr (7) U It is apparent from this discussion of alternative boundary conditions and the various forms of lubricant film shape and hydrodynamic pressure profile that result, that there is the potential to obtain very different values of radial.
As the governing lubrication equation for hydro- dynamic film bearings in laminar and turbulent regimes is a second-order linear partial differential equation , two boundary conditions correspond- ing to the locations where the film pressure starts building up and where it stops are required to evaluate the two constants of integration.
The thickness of lubricating oil film is more than A. The thickness of lubricating oil film is less than A. These are used as such no metallic surfaces are required for adsorption. The thin film of lubricating oil is adsorbed by physical or chemical forces at the metallic surface.
Elastohydrodynamic lubrication (EHL) film thickness and rolling resistance play a critical role in determining friction, wear, life, and other tribological characteristics of rolling bearings. Although film thickness formulas are widely used and experimentally verified, accurate prediction of the film thickness is still difficult under starved.
In industrial applications, a starved lubrication condition may occur, leading to a reduction in film thickness; by modifying the surface geometry, the tribological performance of the contact is enhanced. In this paper, the influence of surface texturing as a method for reducing the friction on the film thickness in parallel sliding surfaces for starved lubricated contacts is investigated.
the formation of lubricating films under both th ick and thin film conditions, viscosity (Rizvi,Ludema,Leslie, and Margareth, et. al., ), affects heat generation in. A lubricant is a substance which accomplishes this. A lubricant is usually a fluid, although it may also be a solid or semisolid, that flows between contact sur-faces to form a film.
Under the best of conditions, the moving parts do not actually make contact, but glide on this film (Figure 2b). Friction is greatly reduced, because the. In conditions where there is inadequate lubricant film thickness between the metal surfaces, the asperity contact points can lead to cold welding, which is the prerequisite for adhesive wear.
The adhesion at these asperity points undergoes a work-hardening process, which strengthens the material. On the Appearance of Lubricant Film Rupture in Cylindrical Journal Bearings Article (PDF Available) in Tribology Transactions 47(2) April with 74 Reads How we measure 'reads'.
Hydrodynamic Lubrication is the culmination of over 20 years close, collaborative work by the five authors and discusses the practical use of the formalization of low pressure lubrication.
The work concentrates on the developments to journal and thrust bearings and includes subjects such as:• the dynamic behaviour of plain and tilting-pads• the thermal aspects• the positive and negative. Boundary lubrication. The oil film has become so thin in Zone 1 that there is no hydrodynamic contribution and only boundary lubrication which is defined by Campbell in as the lubrication by a liquid under conditions where the solid surfaces are so close together that appreciable contact between opposing asperities is possible.
lubricating film is of the same order of magnitude as t he individual oil molecules. This cond ition ma y present when the quantity of oil is insufficient or the relative movement between s. Moreover conditions under which the cavitation phenomenon does not occur are also given.
In the following we will use notation and some results from the book of Childs (6). MODEL OF FILM RUPTURE PHENOMENON Let us study in more detail how the cavitation appears in the case of plain journal bearings under classical lubrication.The book thoroughly addresses all aspects of the topic, from viscosity and rotor-bearing dynamics to elastohydrodynamic lubrication and fluid inertia effects.
Fully worked examples, analytical and numerical methods of solutions, practice problems, and detailed illustrations are .Finally, based on the model proposed by ski, the rupture ratio of the lubricating film was discussed to address why BN-C-silicone oil composite colloid has relatively lower frictional.