摘要:

For specific use in rolling bearing dynamics computer codes, available experimental traction data on some solid lubricants is correlated to a simple algebraic equation defining traction as a function of slip or slide-to-roll ratio. The coefficients of the model are computed by regression analysis of available experimental data and are tabulated for immediate practical use.Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in Orlando, Florida, October 11–13, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982390

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

During fretting, small amplitude displacements and high normal surface loads combined with abrasive oxide particles cause surface damage that acts as initiation sites for fatigue cracks. Since these conditions are prevalent within the titanium dovetail joints of jet engines a wear mode analysis was performed on extended service jet engine disks and compressor blades. The results of the wear mode analysis indicated that titanium from the uncoated disk was transferred to the softer copper-nickel-indium coated dovetail surface of the blades. This transfer created titanium on titanium contact and eventually fretting wear. In order to simulate these conditions, a moderate displacement (125 μm), low cycle phase followed by a small displacement (25 μm), high cycle fretting phase utilizing a cylinder on flat configuration was developed. The analysis and test procedure developed during this study will ultimately aid in the selection and evaluation of a new coating capable of preventing fretting.Presented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982391

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The tribological characteristics of magnetic thin film media coated with perfluoropolyether (PFPE) lubricants (ZDOL and AM300J) and a phosphazene additive (X-IP) were investigated in this study. The drag test results show that under ambient and hot/wet conditions the media coated with AM300J lubricant have higher retention on the test track than those coated with ZDOL 2000 PFPE lubricant. The phosphazene additive X-IP was observed to strongly anchored to the surface and was not as easily removed as PFPE lubricants alone. The retention characteristics of X-IP are independent of either AM or ZDOL. Secondary Ion Mass Spectroscopy (SIMS) depth profile data and Angle-Resolved X-Ray Photo-electron Spectroscopy (XPS) reveal that X-IP molecules were distributed near the disk surface in the X-IP and PFPE lubricants mixed layer, indicating a strong bonding/adhesion of X-IP to the disk surface. Together with the drag testing data, the authors conclude that the preferential distribution of X-IP close to the disk surface in the mixed layer helps to improve lubricant retention performance at the head-disk interface.Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in Orlando, Florida, October 11–13, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982392

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The lubrication condition pertaining to the cross head guide shoe of a low speed cross head diesel engine is evaluated in this paper under the principles of hydrodynamic lubrication. The Reynolds differential equation which describes the pressure and oil film thickness distribution of the cross head guide shoe system operating under unsteady load will be solved using a finite difference method. The influence of the width to length ratio of the rectangular cross head guide shoe plate will be considered in terms of variation of the pressure distribution within the bearing and its load carrying capacity.

ISSN:1040-2004    

DOI:10.1080/10402000008982393

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

There are many problems to be overcome when storage devices are used at high-speed rotation and very small spacing between the head and disk. One of them is lubricant spin-off. Lubricant spin-off and lubricity have a close relation to the molecular weight distribution. The commercial Perfluoropolyether (PFPE), which is widely used as a lubricant for magnetic disks, has a wide molecular weight distribution from several hundred to over ten thousand. In order to improve performance regarding spin-off and lubricity, it is necessary to control the molecular weight distribution.

ISSN:1040-2004    

DOI:10.1080/10402000008982394

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This is the second of two papers giving the results of a study undertaken to determine how aircraft engine oil degrades to form coke on oil-wetted surfaces. In part 2 the authors address the impacts of additives (which is related to oil types) and surface materials upon the oil coking process.

ISSN:1040-2004    

DOI:10.1080/10402000008982395

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Experiments have been conducted on the application of a new type of gas lubricated self-acting journal bearing—plate-foil bearing to a high speed cryogenic turboexpander. The 25.0 mm diameter bearing consists of a rigid housing and a flexible foil element; different structure parameters of the bearing are selected in the experiments. Experimental results indicate the foil bearing presented here offers better system stability performance and high durability, and it confirmed that the application of this type of plate-foil bearing to the cryogenic turboexpander is feasible. The experiment results, including the effect of the plate-foil bearing structure parameters on the rotor-bearing system stability, are described in this paper.Presented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982396

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A vacuum spiral orbit tribometer (SOT) was used to determine the relative lifetimes of a branched perfluoropolyalkylether (PFPAE) on 440C stainless steel. The effect of varying the mean Hertzian stress (0.75, 1.0, 1.5 and 2.0 GPa) and the use of TiC coated balls on lubricant lifetime was studied. Other conditions included: ∼100 rpm, ∼50 μg of lubricant, an initial vacuum level of < 1.3 × 10−6Pa (< 1.0 × 10−8Torr), and room temperature (∼23 °C). Increasing the mean Hertzian stress from 0.75 to 2.0 GPa results in an exponential decrease in lubricant lifetime for both material combinations. However, substituting a TiC ball for the 440C ball quadrupled lifetime at low stress levels (0.75 and 1.0 GPa) and doubled life at higher stresses (1.5 and 2.0 GPa). The reduced reactivity of the TiC surface with the PFPAE lubricant is considered to be the reason for this enhancement. Decreasing lifetime with increasing stress levels correlated well with energy dissipation calculations.Presented as a Society of Tribologists and Lubrication Engineers Paper at the ASME/STLE Tribology Conference in Seattle, Washington, October 1–4, 2000

ISSN:1040-2004    

DOI:10.1080/10402000008982397

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Mixed lubrication is a key to bring the performance analysis to the failure analysis in most tribological components. A macro-micro approach to mixed lubrication has been developed in the present model. The relation between the average contact pressure and the average gap for a typical rough contact patch is first determined numerically in micro scale. Using this relation, the average gap, average oil-film pressure, and average contact pressure in a mixed-lubricated elastohydrodynamic contact can be solved simultaneously in macro scale by treating the contact to be smooth. The total pressure is assumed a superposition of average asperity contact pressure and lubricant pressure. The new approach is simple, efficient and robust, and covers entire range of the load ratio, from unity (dry contact) to zero (full-film EHL). In addition, it can be used for a wide range of operating conditions and on a much larger contact area with a much less computing time than deterministic simulation of mixed lubrication. Implementation of the Fast Fourier Transform (FFT) allows for a rapid calculation of the elastic deformation and asperity con/act pressure. As a demonstration to this new approach, a parametric study of dimensionless speed, load and contact shape on the load ratio and gap ratio was conducted for a gear rough surface of the load ratio, from unity (dry contact) to zero (full-film EHL). In addition, it can be used for a wide range of operating conditions and on a much larger contact area with a much less computing time than deterministic simulation of mixed lubrication. Impletmentation of the Fast Fourier Transform (FFT) allows for a rapid calculation of the elastic deformation and asperity contact pressure. As a demonstration to this new approach, a parametric study of dimensionless speed, load and contact shape on the load ratio and gap ratio was conducted for a gear rough surfacePresented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999

ISSN:1040-2004    

DOI:10.1080/10402000008982398

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper analytically investigates the isothermal line contact elastohydrodynamic lubrication of three lubricants with much different shear strengths under the nondimensional operating parameters of w = 2.15e-4 and U = 2.53e-10 applying the lubricant ideal viscoplastic rheological model. The boundary slippage of the low-shear-strength lubricant occurring in the EHL inlet zone was found and results in a much thinner film compared to the classical EHL theory prediction. The film boundary slippage and its growth with the slide/roll ratio variation of tile low-shear\- strength lubricant exhibit special phenomena, which are much different from those of the high-shear-strength lubricant. The easy occurrence of film failure in concentrated contact in the case of high sliding speed, heavy load, large slide/roll ratio, and low-shear-strength lubricant was concluded due to the severe friction heating on the surface conjunction and the lubricant thermal desorption on tile lubricant/surface boundary. The EHL film failure mechanism was further recognized.

ISSN:1040-2004    

DOI:10.1080/10402000008982399

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor