摘要:

A theoretical model is developed to investigate the effect of Coulomb damping in the sub-foil structure of a foil bearing. Equivalent viscous damping is found for the Coulomb friction. The foil is treated as a continuous perfectly extensible surface on an elastic foundation. The fluid is modeled with the compressible Reynolds equation. A perturbation approach is used to determine the bearing stiffness and damping coefficients from the coupled fluid-structural model. Results are presented for foil bearings with an elastic foundation constructed of a corrugated foil.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983270

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The frictional properties of a novel lubricant on a thin film magnetic medium are presented. The novel carboxylic amine salt has better frictional characteristics than the corresponding amide. The microscopic coverage of the lubricant film on the magnetic medium also is investigated by means of FTIR. Coverage does not change during reciprocating motion for the amine salt, which tightly anchors to the surface, since the friction coefficient is low and steady. The friction coefficient of the amine salt decreases with increasing lubricant on the surfaces. In contrast for the amide, the rubbing contact process breaks the lubricant film and results in high friction coefficient, since the amide has weak interaction with the surfaces. The friction coefficient is almost independent of the amount of the lubricant for the amide.

ISSN:1040-2004    

DOI:10.1080/10402009408983271

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

It has been demonstrated that design optimization of labyrinth seals using the present numerical model is quite beneficial. The results shown include important, but previously unknown effects on the leakage rate, especially that of step height. Further, complete details are given of a very effective seal designed using this technique.

ISSN:1040-2004    

DOI:10.1080/10402009408983272

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effect of face loading, surface roughness and material properties on the static sealing performance of mechanical face seals is analyzed. The analysis combines the problems of contact and flow between two rough surfaces. The results are compared with available experimental data and are found to be reasonable. Based on many numerical results, a simple empirical expression is derived which enables easy and quick evaluation of the effect of the various parameters on seal performance.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983273

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Increased wear occurred in the actual refrigeration compressor when HFC refrigerants were substituted for CFCs to comply with the Montreal Protocol. A cause of this increased wear was believed to be the inferior extreme-pressure (EP) or antiwear capability of the alternative refrigerant HFC-134a as the environment gas, compared to that for CFC-I2 refrigerant which is currently used. However, under some severe conditions, it was found that the alternative also showed some antiwear or EP effect by forming a fluoride layer on a sliding surface.

ISSN:1040-2004    

DOI:10.1080/10402009408983274

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In oscillating contact tests with a polyamide (Nylon 6,6) material against a sapphire optical flat, it was found that tribochemical changes of the polymer occurred at relatively low levels of frictional heat generation, i.e., 15 W. Surface temperatures were measured directly by means of an infrared microscope and reached 200 C for Nylon 6,6. Wear scars and transferred material to the sapphire flat were examined by the use of Fourier transform infrared microspectroscopy (FTIRM). It was found that under the operating conditions used, Nylon 6,6 undergoes a degradation process which yields two kinds of species. The base material on the wear scar is enriched in carbonyl groups while the transferred material and wear debris are enriched in amidelamme groups. A model for tribochemical degradation is proposed. The addition of 10 wt. % glass fibers to Nylon 6,6 reduced wear, friction, surface temperature, and extent of tribochemical degradation.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983275

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper presents an empirical approach for determining the effective lubricant rheological parameters in elastohydrodynamic contacts by using the experimental traction data taken from a conventional two-disc machine apparatus. These effective lubricant rheological parameters as functions of pressure and temperature are currently not available for most of the lubricants in practical applications, and are yet essential for traction calculations in elastohydrodynamic contacts. As a demonstration, comprehensive traction measurements are made with one gear lubricant for its effective rheological parameters. The lubricant parameters obtained are then incorporated into a traction model developed previously, and good agreement between model prediction and experimental observation is shown.

ISSN:1040-2004    

DOI:10.1080/10402009408983276

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Sialon and zirconia-toughened alumina (ZTA) ceramics were evaluated as roller followers in simulated valve train tests. The tests measured the load-carrying capacity of the ceramic rollers by determining when incipient seizure occurred on the steel shaft. The test results revealed that the ZTA rollers exhibited a greater load-carrying capacity compared to the sialon rollers, which was due to the surface texture of ZTA rollers. The bore of the ZTA ceramics exhibited considerable grain pullout, providing cavities to retain the lubricant. It was also observed that a honed bore surface increased the load-carrying capacity of the ceramic rollers compared to the ground bore surface, particularly with the sialon rollers. The diametral clearance had no discernable effect on the maximum load-carrying capacity for the range of clearances tested, which is contrary to analytical models.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993

ISSN:1040-2004    

DOI:10.1080/10402009408983277

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Since the advent of the first numerically controlled machine, the full automation of machine tools has been a central theme in manufacturing engineering research. Especially, the ability to change tools automatically due to tool wear or damage is an essential part of a machining system in the unmanned factory. Although a wide variety of tool failure sensing techniques have been developed recently, few have been successfully implemented in industries and show much limitation in the real application of on-line tool wear sensing.

ISSN:1040-2004    

DOI:10.1080/10402009408983278

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The total power loss of gears was measured in a back-to-back gear test rig. Test equipment, measuring principle and evaluation of the data are described. The influence of different lubricant type, viscosity and temperature on mesh and churning losses was investigated. The churning losses depended mainly on the viscosity of the lubricant and on the operating conditions, not on the lubricant type. The mesh power loss depended mainly on the type of lubricant, not on viscosity, temperature, or oil additives.

ISSN:1040-2004    

DOI:10.1080/10402009408983279

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor