摘要:

An analysis was performed to determine the effects of inner-ring speed and press fits on roller bearing fatigue life. The effects of the resultant hoop and radial stresses on the principal stresses were considered. The maximum shear stresses below the hertzian contact were determined for different conditions of inner ring speed and load, and were applied to a conventional roller bearing life analysis. The effect of mean stress was determined using a Goodman diagram approach. Hoop stresses caused by press fits and centrifugal force can reduce bearing life by as much as 90 percent. Use of a Goodman diagram predicted life reduction of 20 to 30 percent. The depth of the maximum shear stress remained virtually unchanged.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981741

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The scuff-limited load capacity of both hardened and annealed AISI 52100 steel balls sliding against hardened carbon steel flats were investigated. Silicone oils were used us the lubricants. The test flats were prepared by directional grinding to ∼ 250 nm Ra, then abrading with various grades of abrasive paper.

ISSN:0569-8197    

DOI:10.1080/05698198708981742

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

It is proposed that as conditions are made more severe in a dry, sliding contact, a regime is eventually initiated in which friction is governed by heat flow. If is suggested that in any given configuration a maximum allowable sulfate temperature can be defined, two alternate closed-form results for friction can be derived. It is suggested that this regime of friction could be relevant to polymers and elastomers due to their low thermal conductivity. The models are compared quantitatively and quantitatively with results in the literature.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981743

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A variety of MoS2films having different initial surface compositions and different degrees of reaction in oxidizing atmospheres have been prepared by sputter deposition onto 440C steel substrates. The compositions of these films, including their degree of oxidation and their molybdenum-sulfur stoichiometry, have been determined by x-ray photoelectron and Auger electron spectroscopy immediately before the films were subjected to sliding wear tests. These tests, which used, an inhouse, “ring-on-disk” apparatus operating in an inert atmosphere, involved rubbing coated specimens against initially uncoated, polished 440C steel coutersurfaces. Films that had approximately 30 to 40 percent of their surface layers oxidized to MoO3gave the best wear results. In addition, the presence of elemental sulfur in the film surface layers appears to enhance wear life. These data are interpreted to mean that much better adhesion between the transfer film and he initially bare steel surface is obtained through chemical bonding of the transferred MoS2when its surface layers are disrupted by chemical modification.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981744

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A novel test apparatus was built to measure the interface friction between a single cam-lifter pair isolated from other frictional components in the value train. Detailed investigations were made, for both a conventional lifter and a roller lifter. Measured results showed an 80 percent reduction in friction with the use of the roller lifter and the trend of decreasing friction with engine speed for both types of lifters. The observed lack of friction reduction over any part of the contact cycle and the large coefficient of friction in the case of the conventional lifter ruled out the possibility of elastohydrodynamic lubrication at the contact.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981745

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A simplified, semianalytical model has been developed to analyze the effect of centrifugal inertia in two-phase face seals. The model is based on the assumption of isothermal flow through the seal, but at an elevated temperature, and takes into account heat transfer and boiling. Using this model, seal performance curves are obtained with water as the working fluid. It is shown that the centrifugal inertia of the fluid reduces the load-carrying capacity dramatically at high speeds and that operational instability exists under certain conditions. While an all-liquid seal may be starved at speeds higher than a “critical” value, leakage always occurs under boiling conditions.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981746

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

An accelerated-wear test apparatus was developed to screen bearing-flange materials. During the test, tape edges rub against two flat test specimens (which are easy to fabricate). The clamping arrangement of the specimens provides the same contact with the tape during repeated tests. The tape is loaded against the sample by deadweight loading, which ensures constant loading, irrespective of tape guiding. Acceleration in wear is obtained by increasing the load at the interface of the tape and the test specimen. Wear tests were conducted on several metals, ceramics and cermets, coatings, and surface treatments. We find that ceramics and cermets have the lowest wear.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981747

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The influence of pressure on the density of six base fluids was experimentally studied for a range of pressures from 0.422 to 2.20 GPa. An important parameter used to describe the results is the change in relative volume with change in pressure dvr/dp. For pressures less than the solidification pressure (p < ps), a small change in pressure resulted in a large change in dvr/dp. For pressures greater than the solidification, pressure (p > ps), there was no change in dr/dp with changing pressure. The solidification pressures of the base fluids varied considerably, as did the slopes that the experimental data assumed, for p < pv. A formula was developed that describes the effect of pressure on density in terms of four constants. These constants vary for the different base fluids tested.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981748

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The Amontons-Coulomb law of sliding friction is used to analyze a line contact elasticity model in which the contact stresses and tangential displacement relevant to fretting fatigue are calculated. Once the numerical analysis is verified, the effects of finite thickness and tangential loading are calculated and their influence on fretting fatigue is discussed. The results are shown to compare well with previous experimental observations on a qualitative basis and a refinement of the model that would lead to quantitative experimental comparisons is suggested.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981749

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The oxidation characteristics of a pure ester (trimethyolpropane triheptanoate) were studied by using a chemiluminescence technique, Test were run in a thin-film microoxidation apparatus with an aluminum alloy catalyst. Condition included a pure oxygen atmosphere and a temperature range of 176 to 206°C. Results indicated that oxidation of the ester (containing 10−3M diphenylanthracene as an intensifier) was accompanied by emission of light. The maximum intensity of light emission (Imax) was a function of the amount of ester, the concentration of intensifier, and the test temperature. The induction period or the time to reach one-half of maximum intensity (t½) was an inverse function of test temperature. Decreases in light emission at the later stages of a test were caused by depletion of the intensifier.Presented at the 41st Annual Meeting in Toronto, Ontario, Canada May 12–15, 1986

ISSN:0569-8197    

DOI:10.1080/05698198708981750

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor