摘要:

Comparisons were made between theoretical calculations and experimental measurements for minimum bearing oil film thickness (MBOFT) in main and connecting rod bearings of a typical automotive V6 engine running at 1500 rpm under three load conditions (64, 128, and 192 Nm.). Data for five oils (SAE grades 5W–20, 20W–20, 5W–30, 10W–30, and 20W–50) were obtained for the main bearing and for two oils (SAE 5W–30 and 10W–30) for the connecting-rod bearing. The theoretical calculations were done using the FLARE computer code while the measurements were made using the total capacitance method (TCM).

ISSN:1040-2004    

DOI:10.1080/10402000008982350

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

It has been reported in the literature that overbased detergents can possess good antifriction and antiwear properties although the origins of these properties are not fully clear. In practice, over-based detergents are colloidal dispersions and this may be important in determining their properties and mechanism of action.

ISSN:1040-2004    

DOI:10.1080/10402000008982351

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The relationship between growth of rolling contact fatigue cracks and load distribution on an inner ring of the radial rolling bearing was investigated by a new acoustic emission (AE) source location method. The histograms of cumulative AE events at possible AE source positions located in rolling contact fatigue tests were compared with the location results given by a numerical simulation. In many tests, the location histograms were not symmetric and most of the peaks in the histogram were distributed behind the actual AE source position. These corresponded to the simulation where the effective area for propagation of the fatigue crack deviated to the entrance side for the rotational direction within the loading zone. From the comparison, it became clear that the fatigue crack had a tendency to propagate in a narrow area deviating to the entrance side in the early stage of its growth and the area spread to the exit side gradually with the growth process from the initiation of the fatigue crack to an appearance of spoiling.Presented at the 55th Annual Meeting Nashville, Tennessee May 7–11, 2000

ISSN:1040-2004    

DOI:10.1080/10402000008982352

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This study presents an engineering approach for optimizing performance of fluid-film lubricated bearings. Unconstrained nonlinear programming methods, lattice search and simplex method, were used as the optimization schemes to improve the merit of studied bearings with two or more design variables. The analysis of elliptical bearings shows high eccentricity ratio and two large pressure zones for high-speed stability can be obtained by maximizing film pressures in the upper and lower lobes. In this study, lattice method exhibits slightly more efficient search compared with that of simplex method in several two-variable optimum designs. The automatic mesh generation technique used in the pocket-shaped bearing analysis makes the numerical optimization as a flexible design tool. The effect of side flow restrictions on the load-carrying capacity of an optimized pocket-shaped slider bearing is clearly verified. The analysis of the aerostatic bearing explains an example of multi-objective minimization. A similar procedure can be easily adopted to analyze bearings with other profiles, or to maximize user-defined performance using more complicated models.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:10.1080/10402000008982353

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In recent years there has been considerable interest in employing dispersed, solid colloidal panicles in the 1–500 nm diameter range to enhance the friction and wear characteristics of liquid lubricants. One important question concerning the use of these additives is the extent to which the tiny solid particles pass through rolling and sliding contacts.

ISSN:1040-2004    

DOI:10.1080/10402000008982354

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Blisters that develop on carbon-graphite mechanical seal faces are irregularities in surface topography that result in poor sealing performance and a high incidence of catastrophic failure. On first inspection, a blister is a burnished area that is slightly elevated above the surrounding seal surface. In this study, the topography of several hundred blisters was examined with interference microscopy. The shape of the burnished area is typically elliptical or cylindrical. The leading edge against the direction of rotation of the mating seal ring extends abruptly upward from the surrounding seal surface. The trailing surface gradually merges into the parent seal face. Most blisters have a maximum height of 0.25 μm to 0.75 μm (10 μ-in to 30 μ-in).Presented at the 55th Annual Meeting Nashville, Tennessee May 7–11, 2000

ISSN:1040-2004    

DOI:10.1080/10402000008982355

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this study a dynamic bearing apparatus is designed, developed and used to evaluate noise and vibration of bearings lubricated with various greases under different operating conditions. Eight different greases are evaluated for their vibration and noise characteristics. The threshold, kurtosis and mean square methods are used to quantify grease vibration and rank the greases based on their bearing vibration. The results indicate that ultra-filtered greases exhibit the lowest bearing vibration in the mid-frequency range amongst all greases tested.Presented at the 55th Annual Meeting Nashville, Tennessee May 7–11, 2000

ISSN:1040-2004    

DOI:10.1080/10402000008982356

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A Finite Element model for the noncontacting gas face seal is developed based on the modified Reynolds Equation developed by Fukui and Kaneko (4), (5) that considers the slip flow effects. Numerical studies of a representative spiral groove seal at the slow speed (≤, 500 rpm) and the low pressure (≤ .303 MPa) conditions showed that slip flow can significantly affect the seal performances such as the lift-off speed, leakage rate, load carrying capacities. Without the consideration of the slip flow effect, the lift-off speed and the corresponding leakage rate would be greatly underestimated, especially at near ambient pressure condition. By examining the F-h characteristic curves, it was found that under the parameters presented in the present study the slip flow could be significant for Knudsen number, Kn as small as .05, and the slip flow in effect reduces the viscous pumping resulting in a loss of load carrying capacities.Presented at the 55th Annual Meeting Nashville, Tennessee May 7–11, 2000

ISSN:1040-2004    

DOI:10.1080/10402000008982357

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A novel analytical approach for piston ring lubrication solution is presented by taking proper account of mass conservation in the cavitated region (JFO boundary conditions). A system of five nonlinear equations is employed to calculate such parameters as oil film thickness, frictional force, power loss, and oil flow rate. For an enclosed cavitation pattern in piston-ring assembly it was found, that JFO boundary conditions give much better accounting of the estimation of friction force, power loss and flow rate. To show the effectiveness of the undertaken approach, the widely accepted Jeng's approach (Jeng, 1992a) was selected, in which the pressure contribution from the cavitated and the second full film regions, as well as the trailing edge pressure, are ignored.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:10.1080/10402000008982358

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A thermal model is presented in this paper for deterministic calculations of the contact temperatures in mixed-film lubrication. A first-principal approach is taken to obtain the temperature results by solving transient energy equations in a domain consisting of three solid-film-solid regions. Various modeling techniques are used to feature model simplicity and to achieve a proper balance among solution accuracy, model robustness and computational efficiency. This thermal model may be incorporated into other deterministic isothermal mixed-film models to form a complete base model for mixed-film lubrication. It provides a platform upon which to model other effects such as lubricant additives, asperity plastic deformation and surface coating.

ISSN:1040-2004    

DOI:10.1080/10402000008982359

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor