摘要:

In this paper, a new numerical algorithm is presented to predict gaseous cavitation in various fluid film bearings. Elrod's universal differential equation is transformed into a generalized boundary integral equation, which is valid throughout both the full film and the cavitated regions. The mathematical development of the algorithm couples the boundary discrete element and internal integral cell techniques. A computer code for linear elements is developed. Three types of bearings, a parabolic slider bearing, a submerged journal bearing, and a grooved journal bearing, are investigated. The results are compared with those obtained by use of the finite difference method. The advantage of the algorithm is clearly demonstrated by its computational accuracy and solution speed.Presented as a Society of Tribologists and Lubrication Engineers paper at the STLE/ASME Tribology Conference in New Orleans, Louisiana, October 24–27, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983286

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Journal pad bearings are widely used in industry, particularly in high-speed applications. Previous experimental work with bearings of this sort has tended to be fragmented and mainly confined to smaller and relatively lightly loaded bearings. The purpose of this paper is to present temperature measurements and derived values of power loss from a new, extensive experimental program involving a 200 mm diameter journal pad bearing, operating at speeds up to 105 m/s and loaded at specific pressures up to 4.14 MPa. The program was designed to isolate some important design parameters and determine their effect on bearing temperatures and energy consumption. Bearing clearance, journal pad preload, the direction of the applied load, and the impact of radically reducing the amount of lubricant supplied to the bearing are all examined. In particular, it is found that load line direction has a substantial impact on maximum pad temperature. It is also shown that large reductions in the volume of oil supplied to the bearing are possible, leading to useful energy savings without compromising reliability. One of the most interesting features of the results presented is the significant effect on pad temperature of an apparent laminar to turbulent transition in the lubricant which occurs at high operating speeds. It is hypothesized that the transition takes place in the oil which flows around the pads rather than in the hydrodynamic films. It is anticipated that the information contained in the paper will be of interest and use to members of the academic community, bearing designers, and bearing operators.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983287

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A predictive pitting model for gear design applications was recently developed by Blake and Cheng (1), (2). Life estimates were based on predicting the growth of surface-breaking cracks leading to pit formation. While trends predicted by the model reflected observed behavior, estimated lives were lower than expected. The crack growth model has been improved by modifying the original shear-driven, two-dimensional propagation model to reflect three-dimensional cracks driven by both shear and lubricant pressure effects. Resistance to crack growth due to friction between the crack faces has also been considered. These changes have led to a net increase in predicted lives, which better reflects observed pitting behavior.Presented at the 46th Annual Meeting in Montreal, Quebec, Canada April 29–May 2, 1991

ISSN:1040-2004    

DOI:10.1080/10402009408983288

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A mechanism of thermocracking, which occurs in an alumina ceramic ring of a mechanical face seal, is proposed based on experimental and analytical results. Methods for its prevention are also discussed. The experiments were conducted using an external type mechanical face seal composed of a carbon ring and three kinds of alumina ceramic rings, with distilled water as the liquid to be sealed. By using a layer of gold vacuum deposited onto the surface of the ceramic ring as a part of a DC circuit, the moment of crack initiation was identified. The thermal stresses produced in the ceramic ring by frictional heating were calculated using finite element analysis.

ISSN:1040-2004    

DOI:10.1080/10402009408983289

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Previous studies have demonstrated that the durability of some fuel injection systems on compression-ignition engines will be adversely affected by fuels of sufficiently low lubricity. However, no widely, accepted lubricity measure is available; indeed, the wear mechanisms present have not been conclusively defined. The results of the present study indicate that oxidative corrosion is the predominant mechanism with very highly processed fuels, resulting in catastrophic wear and rapid failure. Less highly refined fuels contain natural corrosion inhibitors and produce alternate wear mechanisms that may still affect long-term durability. A laboratory test procedure directed toward the oxidative wear mechanism was evaluated and a number of modifications suggested. The resulting test produced good correlation with the full-scale pump and appeared to correlate with the criteria necessary for oxidative corrosion. However, it is recognized that this single test procedure may not fully define the lubricity requirements of the injection system, particularly in the absence of oxidative corrosion or very highly loaded contacts that are susceptible to adhesive wear and scuffing.Presented as a Society of Tribologists and Lubrication Engineers paper at the STLE/ASME Tribology Conference in New Orleans, Louisiana, October 24–27, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983290

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Ball bearings experiencing small angular oscillations have been shown to trace out hysteresis loops. The hysteresis torque of ball bearings can be characterized by two parameters: the steady rolling friction torque Tsand the rest slope σ. Accurate prediction of these parameters is crucially important to designers, as the control of slowly rotating systems that use ball bearings is often dependent on hysteresis torque. This paper contains the development of an empirical expression for σ and a series of experimental investigations which establish and confirm relationships for the rest slope and steady torque behavior. Furthermore, the dependence of σ and Tson the ball diameter is discussed. Excellent correlation is found between theoretical predictions and experiments conducted on an elementary three-ball system specially designed to determine rest-slope and steady torque values.Presented at the 47th Annual Meeting in Philadelphia, Pennsylvania May 4–7, 1992

ISSN:1040-2004    

DOI:10.1080/10402009408983291

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In this paper, modeling of the rotor motion in a jewel bearing is presented. Due to the presence of dry friction forces between the steel tip of the rotor and the cup sapphire surface, the rotor motion no longer consists only of pure rotation. The secondary motion based on the deviation from pure rotation, as well as the driving torque variations (sensitivity threshold) are determined and three basic cases are studied, i.e., the arbitrary position and initial driving torque at the time of motion initiation, the asymptotic position and driving torque which supports pure rotation, and the self-centering process, i.e., the transition from the rest state to pure rotation. The investigation is supported and validated by numerical simulation.Presented at the 47th Annual Meeting in Philadelphia, Pennsylvania May 4–7, 1992

ISSN:1040-2004    

DOI:10.1080/10402009408983292

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Tin coatings on Al-Si alloys are widely used in the automotive industries. The soft tin coating and the harder substrate alloy form a tribological system with the advantages of low friction and reasonably high load-bearing capacity. Wear tests of tin coated Al-Si Z332 alloy in conformal contact against carburized 1016 steel have been carried out under mixed lubrication with SAE WW30 oil to study the wear, mechanisms. Two major wear mechanisms, uniform wear of the tin coating due to micro-plowing and spall pitting related to the substrate are found to contribute to the bearing material loss when the fluid lubrication film is relatively thick (A about 1.6). Under conditions of thinner films (A ˜ 0.8), some local coating debonding occurs. The pitting and local coating debonding are closely related to fracture in the substrate. The bonding between silicon and tin seems to be weaker than between aluminum and tin. During wear, oxidation occurs.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in San Diego, California, October 19–21, 1992

ISSN:1040-2004    

DOI:10.1080/10402009408983293

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A new type of bearing test rig has been set up for static and dynamic tests of oil-film journal bearings.

ISSN:1040-2004    

DOI:10.1080/10402009408983294

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A three-ball-on-disk (TBOD) bench test has been developed to evaluate high-temperature liquid lubricants such as the polyphenyl ethers. The TBOD test method is capable of generating an integrated set of tribo-measurements including friction, wear, lubricant consumption, and lubricant tribochemistry. Unlike the four-ball wear test, well-defined wear scars of circular and elliptical shapes are exclusively produced, which is critical for precise wear volume calculation.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983295

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor