摘要:

A brief history of the development of the idea that static and kinetic frictions are somehow different is presented. The investigations which produced data promoting this idea are discussed and, in each case, the conclusions are examined and shown to be questionable on the basis of other data. Evidence is presented which supports a unified theory of friction with the suggestion that there is, in reality, no static friction. Published static coefficients of friction should be, in the main, considered questionable because of the lack of appreciation for specimen cleanliness and roughness and the important role of atmospheric contaminants upon friction. The proposal is made that all friction is kinetic and the theory needs only to include a sliding velocity parameter to satisfy that portion which was formerly called static friction.Presented at the 28th ASLE Annual Meeting in Chicago, Illinois, April 30—May 3, 1973

ISSN:0569-8197    

DOI:10.1080/05698197408981440

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A solution of the Reynolds equation for finite bearings with exponential film shape and variable viscosity is presented. The field of temperatures is also investigated, by solving the Energy equation. Therefore, the uncoupling of Reynolds and Energy equations is obtained, by using a relationship between viscosity and film thickness. The solution may be used either for plane or convergent curved surfaces with a satisfactory accuracy, as shown by the diagrams of pressure and temperatures. The formulas are given in closed forms, either for adiabatic films or constant temperature boundaries, thus allowing rapid calculations. Furthermore, formulas for the overall characteristics are available, which may be directly used in bearing design.

ISSN:0569-8197    

DOI:10.1080/05698197408981441

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The hypothesis that scuffing of surfaces lubricated by a plain mineral oil results from desorption is tested for high speed cases using two types of apparatus. One uses a medium speed, 1-inch steel ball, 4-ball machine, and a simulated oil consisting of hexadecanoic acid in hexadecane. This lubricant is shown to behave in the same fashion at medium speeds as it does at very slow speeds. Thus, a graph of logarithmic concentration of acid against reciprocal absolute scuffing temperature gives a good straight line, just as at slow speeds. In the second high speed gear tester, the rise in scuff load of gears at very high speeds, the Borsoff effect, can be explained semiquantitatively by considering the residence time of molecules. These two types of results suggest that the desorption-failure mechanism may be valid over the whole rubbing speed range, and not merely at the very low speeds normally tested.Presented at the 28th ASLE Annual Meeting in Chicago, Illinois, April 30–May 3, 1973

ISSN:0569-8197    

DOI:10.1080/05698197408981442

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Proper pressure balancing of gas film seals requires knowledge of the pressure profile load factor (load factor) values for a given set of design conditions. In this study, the load factor is investigated for subsonic and choked flow conditions, laminar and turbulent flows, and various seal entrance conditions. Both parallel sealing surfaces and surfaces with small linear deformation were investigated. The load factor for subsonic flow depends strongly on pressure ratio; under choked flow conditions, however, the load factor is found to depend more strongly on film thickness and flow entrance conditions rather than pressure ratio. The importance of generating hydrodynamic forces to keep the seal balanced under severe and multipoint operation is also discussed.

ISSN:0569-8197    

DOI:10.1080/05698197408981443

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The finite slider bearing profile is sought which maximizes the load carrying capacity for a given minimum film thickness. Several suboptimization problems in the “space” of stepped profiles are considered. The efficient application of the finite element method to the incompressible lubrication problem is outlined.

ISSN:0569-8197    

DOI:10.1080/05698197408981444

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A gradient method is described which can be used to solve problems in elastohydrodynamics. The method involves the minimization of an error function, and is compatible with such numerical schemes of solving continuum problems as the finite element or the finite difference method. A finite length slider bearing is used to illustrate the method, and numerical results for the elastohydrodynamic pressure distribution are presented.

ISSN:0569-8197    

DOI:10.1080/05698197408981445

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A new type of hydrostatic thrust bearing of all-metallic construction is described, in which inherent compensation is provided by the inclusion of a flexible plate. The behavior of a particular form of this bearing was studied theoretically, examined experimentally and found to offer certain advantages over conventionally compensated rigid bearings.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–10, 1973

ISSN:0569-8197    

DOI:10.1080/05698197408981446

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The use of porous materials in externally pressurized thrust bearings is attractive. Compared with conventional externally pressurized bearings, there is a more even distribution of pressure at the thrust face and an external restrictor is not required, which leads to a compact design.

ISSN:0569-8197    

DOI:10.1080/05698197408981447

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

ASLE TRANSACTIONS welcomes the comments and suggestions of readers with regard to papers published in its pages or concerning topics of interest to those engaged in any phase of lubrication engineering. Letters received cannot be acknowledged, but those felt to be of interest to other readers will be published. The Society will not be responsible for the statements or opinions expressed.

ISSN:0569-8197    

DOI:10.1080/05698197408981448

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The storage and operational life of instrument ball bearings are greatly improved by barrier films—thin films of fluorinated organic polymers applied to specific metallic areas to prevent lubricant migration. Current difficulties in determining barrier-film location, a factor critical to effective barrier performance, are shown to be alleviated by incorporating long-lived fluorescent indicators in the solutions used to prepare the barriers. The resulting films exhibit useful levels of fluorescence under ultraviolet radiation after solidificationin situand prolonged storage at relative humidities below 50 percent. Fluorescence decreases with storage at high humidities, but moisture sensitivity of the indicator provides no greater a limitation than does corrosion sensitivity of the bearings. Retention experiments with chlorinated silicones and contact angle measurements with additional liquids show barrier performance to be unaffected by the fluorescent indicator. Therefore, incorporation of long-lived fluorescing components in barrier film formulations is recommended.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973

ISSN:0569-8197    

DOI:10.1080/05698197408981449

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor