摘要:

A test rig has been designed to quantify the torque transmission characteristics of wet clutches. This apparatus is presented and its features discussed. A comparison is made between the torque measurements from the test rig and simulations using a previously developed mathematical model. Results are given for a variety of operating conditions. The data presented here validate the computational model as an accurate tool for wet clutch design and analysis. Important results include accurate torque transfer prediction capabilities, with the limiting factor being precise knowledge of the sliding friction coefficient μc. Another important conclusion of the work is that torque transfer during a single engagement event can be adequately predicted using the isothermal model presented here. The simplicity of the isothermal model, along with its computational efficiency, makes it attractive for wet clutch torque transfer prediction and wet clutch design.Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997

ISSN:1040-2004    

DOI:10.1080/10402009708983691

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Contact start-stop (CSS) tests and continuous drag tests are used for detailed in situ analysis of wear mechanisms in magnetic thin-film rigid disks. Coefficient of static friction and disk surface reflectance are measured during the contact start/stop tests and coefficient of kinetic friction, acoustic emission rms, acoustic emission count, and disk surface reflectance are all measured during the continuous drag tests. It is the first time that friction, acoustic emission and optical reflectance sensors are used simultaneously for wear studies. In situ measurements are used to determine precursors to failure of magnetic thin-film disks, to compare wear processes in CSS and drag tests, and to correlate CSS and drag tests. Disk wear is seen to follow a pattern of lubricant depletion and/or localized polishing of overcoat asperities. The sliding distance associated with CSS tests is less damaging to disks than continuous drag sliding distances. A combination of sensors used in this study, in particular an optical sensor used to measure changes in disk reflectance, has been demonstrated to be valuable in understanding the failure mechanisms.Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997

ISSN:1040-2004    

DOI:10.1080/10402009708983692

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The thermal distortion of mechanical seal faces has a critical impact on the performance of the seal. Experimental work is discussed which quantifies the thermal characteristics of a mechanical seal and its operating environment. Experimental techniques are employed which measure the seal face torque, thermal gradients, and fluid flow patterns under the normal operating conditions of the seal. The experimental data is used to calculate the heat that is generated at the seal faces and the Nusselt number on the wetted surfaces on the stationary element. The experimentally determined Nusselt numbers are compared to experimental and empirical values that have been presented by other researchers. The effect of the seal geometry on the experimental Nusselt numbers is evaluated.Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997

ISSN:1040-2004    

DOI:10.1080/10402009708983693

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Oil-in-water (O/W) emulsions are widely used in metal rolling and cutting and also as fire-resistant hydraulic fluids. For both of these applications they require a reasonable degree of lubricating ability—in metal rolling to protect the surfaces against wear and seizure and to provide a controlled value of friction, and in hydraulics to limit the extent of wear, scuffing and fatigue of rubbing pump components.

ISSN:1040-2004    

DOI:10.1080/10402009708983694

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Cylindrical, sliding contact bearings made entirely of the self-lubricating powder metallurgy composite (PM212) or of superalloy shells lined with clad PM212 were tested in an oscillating mode at temperatures from 25° to 700°C. Tests of 100-hour duration or longer were conducted with the journal oscillating ± 15° at a frequency of 42 cycles/min and at a bearing unit load of 3.45 MPa (500 psi). Shorter duration tests at various unit loads up to 24.2 MPa (3500 psi) were also conducted. In comparison tests, bearings lubricated with PM212 had lower friction and superior antiwear characteristics compared to the baseline, unlubricated, superalloy bearings. No galling of PM212-lubricated bearings occurred, while severe surface damage including galling occurred, especially at high loads, during the baseline tests. A heat treatment procedure, which dimensionally stabilizes PM212 and thereby minimizes clearance changes during high temperature bearing operation, is described.Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997

ISSN:1040-2004    

DOI:10.1080/10402009708983695

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A selection of liquid lubricants was vaporized and deposited on a hot, 705°C (1300°F), ceramic surface. Friction was then evaluated in low speed, 7 MPa (1000 psi), sliding contact. The ceramic materials included aluminum oxide, silicon aluminum oxynitride (SiAlON), silicon nitride, and silicon carbide. Each specimen was mated with an equally hot specimen of the same material. Deposits reduced friction significantly compared to the unlubricated contact.

ISSN:1040-2004    

DOI:10.1080/10402009708983696

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The influence of mechanical action and tribochemical effects on the material removal mechanism during accelerated wear of silicon nitride balls was investigated. It was found that the tribochemical effects are more effective in material removal than the mechanical action of abrasive particles present in the slurry. Mechanical action is governed by the applied load, amount of slip within the contact area and the size of abrasive particles, while tribochemical effects depend mainly on the type of lubricating liquid used and the chemical nature of additives.

ISSN:1040-2004    

DOI:10.1080/10402009708983697

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A Reynolds-type equation for finite hydrodynamic bearings, (plane slider and cylindrical journal), with rough surfaces (longitudinal, transverse and isotropic roughnesses), has been solved using the stochastic finite element method considering film thickness to be a stationary, ergodic stochastic process with mean zero. Mean steady-state characteristics have been obtained and compared with those obtained by previous investigators. The effect of a spatially randomly varying component of roughness has been studied by giving different input standard deviations of film thickness and calculating output standard deviation of maximum pressure for different scales of fluctuation using the first-order second-moment method.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in San Francisco, California, October 13–17, 1996

ISSN:1040-2004    

DOI:10.1080/10402009708983698

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Debris in lubricated contacts significantly reduces the contact fatigue life. The life reduction is due to the surface damage caused by debris denting and the subsequent overrolling of the dent in the EHL contact. High pressure spikes are generated due to the dent which will modify the contact stress profiles, leading to stress concentration at or near the surface. In this paper, the residual stresses caused by debris effects are investigated. The residual stresses originate from the debris denting process and from the overrolling process of the dent in EHL contacts. The finite element method was used to investigate the residual stresses due to each process and their combined effects on the internal stress distribution of an EHL contact. It was found that the residual stress from debris denting will increase the internal stresses in an EHL contact. However, the residual stresses from overrolling of dent will reduce the internal stresses. The residual stresses are largely dependent on the plastic modulus of the contacting materials and need to be considered when investigating the internal stresses in heavily loaded lubricated contacts.Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997

ISSN:1040-2004    

DOI:10.1080/10402009708983699

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The repeated wear tests between a ferromagnetic pin and a paramagnetic rotor indicate that the abrasive action of the wear particles attracted to the pin by magnetic force increases the wear amount of the rotor when the difference in micro-Vickers hardness between the wear particles and the rubbing surface of rotor exceeds 100. Furthermore, the pin magnetized by AC current for a virgin surface increases wear.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in San Francisco, California, October 13–17, 1996

ISSN:1040-2004    

DOI:10.1080/10402009708983700

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor