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AWARDS

J. of Lubrication Tech. 1977;99(2):145-146. doi:10.1115/1.3452996.
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Abstract
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):179. doi:10.1115/1.3453010.
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Abstract
Commentary by Dr. Valentin Fuster

REPORTS

J. of Lubrication Tech. 1977;99(2):147-151. doi:10.1115/1.3452997.
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Abstract
Commentary by Dr. Valentin Fuster

RESEARCH PAPERS

J. of Lubrication Tech. 1977;99(2):152-156. doi:10.1115/1.3452998.

The Spectrographic Oil Analysis Program (SOAP) is a standardized procedure for spectrochemically determining the average analysis of all particles present in a sample of oil from hydraulic or lubricated systems. In the present program scanning electron microscopy (SEM) and X-ray analysis were employed to study the morphology and chemistry of individual particles collected from oil samples. Also, a large collection of particles could be studied for obtaining an average analysis of all the particles in the analyzed area. Comparisons of SEM/X-ray data with SOAP data, and their correlation with conditions of parts showed good correlation for the aluminum-containing particles in the aircraft hydraulic system. Though not detected by SOAP, SEM/X-ray analysis showed several particles containing silicon (identified mostly as silica with X-ray diffraction), most of which were typically larger than 5 microns.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):158-162. doi:10.1115/1.3453002.

An investigation of the surface migration of thin films of hydrocarbon oil on metal substrates has been undertaken to determine the effect of temperature gradients on the distribution of lubricants in spacecraft mechanical assemblies. The results of experiments performed in air were discussed earlier. We now discuss the results of experiments performed under vacuum. The important role played by surface finishes is demonstrated. Mathematical models of these results are developed.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):163-172. doi:10.1115/1.3453003.

Fluid flow and mass transport mechanisms associated with articular cartilage function are important biomechanical processes of normal and pathological synovial joints. A three-layer permeable, two-phase medium of an incompressible fluid and a linear elastic solid are used to model the flow and deformational behavior of articular cartilage. The frictional resistance of the relative motion of the fluid phase with respect to the solid phase is given by a linear diffusive dissipation term. The subchondral bony substrate is represented by an elastic solid. The three-layer model of articular cartilage is chosen because of the known histological, ultrastructural, and biomechanical variations of the tissue properties. The calculated flow field shows that for material properties of normal healthy articular cartilage the tissue creates a naturally lubricated surface. The movement of the interstitial fluid at the surface is circulatory in manner, being exuded in front and near the leading half of the moving surface load and imbibed behind and near the trailing half of the moving load. The flow fields of healthy tissues are capable of sustaining a film of fluid at the articular surface whereas pathological tissues cannot.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):174-178. doi:10.1115/1.3453007.

Certain bearing applications require the use of a lubrication system contained within the bearing housing and independent of any outside systems or power sources. Marine main propulsion lineshaft bearings often fall into this category and the use of a disk-scraper system for oil supply represents one solution. Tests on two sizes of such lubricating systems were conducted to determine flow rates and the influence of the primary variables involved. The test data is presented and correlated to assist in the design of this type of lubrication system.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):180-184. doi:10.1115/1.3453011.

A finite element method is used to determine the pressure distribution for a sector pad of a thrust bearing. The optimization technique known as pattern search is applied to the load capacity as a function of the pocket boundary and pocket depth. An optimum ratio of effective length to width is discovered and the optimum pocket geometry, associated two dimensional pressure distribution, power dissipation, center of pressure, and maximum load capacity are calculated for bearings of various curvature and degree of arc.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):187-194. doi:10.1115/1.3453016.

Systems of finite elements are organized using matrix notation for finite length bearings. Most fluid film bearings have surface areas which can be divided into a grid of elements whose nodes are labeled in matrix form. The resulting equations for nodal pressures are block tridiagonal and the solution is easily obtained with direct methods. Analysis of both general slider and journal bearings is included. The choice of how the film is divided into elements can significantly affect the error involved in the numerical solution and some criteria are developed for optimizing the division scheme. In the analysis of a square squeeze pad of uniform thickness, choosing the diagonal sides of elements nearly perpendicular to the pressure gradient direction gives an error in the calculated load carrying capacity of over two times that obtained by aligning element diagonal sides approximately with the pressure gradient direction. For rotating bearings, varying the grid spacing in the circumferential direction directly as the film thickness and properly choosing diagonal alignment can significantly reduce computer time.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):198-210. doi:10.1115/1.3453021.

Bearing impedance vectors are introduced for plain journal bearings which define the bearing reaction force components as a function of the bearing motion. Impedance descriptions are developed directly for the approximate Ocvirk (short) and Sommerfeld (long) bearing solutions. The impedance vector magnitude and the mobility vector magnitude of Booker are shown to be reciprocals. The transformation relationships between mobilities and impedance are derived and used to define impedance vectors for a number of existing mobility vectors including the finite-length mobility vectors developed by Moes. The attractiveness and utility of the impedance-vector formulation for transient simulation work is demonstrated by numerical examples for the Ocvirk “π”, and “2π” bearing impedances and the cavitating finite-length-bearing impedance. The examples presented demonstrate both bearing and squeeze-film damper application. A direct analytic method for deriving a complete set of (analytic) stiffness and damping coefficients from impedance descriptions is developed and demonstrated for the cavitating finite-length-bearing impedances. Analytic expressions are provided for all direct and cross-coupled stiffness and damping coefficients, and compared to previously developed numerical results. These coefficients are used for stability analysis of a rotor, supported in finite-length cavitating bearings. Onset-speed-of-instability results are presented as a function of the L/D ratio for a range of bearing numbers. Damping coefficients are also presented for finite-length squeeze-film dampers.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):215-222. doi:10.1115/1.3453025.

Herringbone grooved journal bearings can have full liquid film lubrication without a continuous external lubricant supply. An attempt has been made to determine the operating conditions at which no leakage occurs. In the many experiments performed with transparent housings the speed was raised until breakdown of the air-to-liquid interface in the bearing gap occurred, and hence leakage commenced. It appears that breakdown of the interface in a completely grooved bearing can be such that it leads to leakage either via the plain surface or via the grooved surface of the bearing. Some speculative theories concerning the breakdown of the interface are considered.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):224-229. doi:10.1115/1.3453029.

Experimental measurements are reported for flow in a cylindrical annulus, with moving inner surface and a step on the stationary outer cylinder. This is related to bearing flows near steps. Strong effects of convected inertia are observed, and these are subdivided into three major classifications. Simplified analyses which include the major physical influences in each category are developed, and are shown to be in reasonable agreement with the measurements.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):230-234. doi:10.1115/1.3453030.

Aluminum alloy workpieces of different roughness, lubricated with graphite, P.T.F.E., lead or polyethylene, were upset between overhanging dies. Measurements of the width of the unlubricated zone formed at the workpiece edge indicated that the rates of outward transport of the lubricants were increased by roughening the workpiece. This was in agreement with a simple analytical model of the lubrication process.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):236-244. doi:10.1115/1.3453040.

The concept of the optimal wearpath is helpful in determining the geometrical formation of the wear scar due to repeated contact loading. By definition it is that shape which alleviates the critical contact failure parameter(s) the fastest way. In the present paper the mathematical formalism is set forth for the ensuing optimization problem. The general prescription for formulating a wear law for a specific application (sliding, rolling, impact, and hybrids) is to combine the wear mechanism with the optimal wearpath. Examples for impact wear are presented, using both macroscopic and microscopic wear models.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):247-253. doi:10.1115/1.3453051.

The effects of cooling on thermoelastic instability are delineated for a two dimensional flat plate geometry. The analysis includes conductive heat transfer from the edge of the flat plate as well as convective heat transfer from its sides. Cooling is found to be characterized by two dimensionless parameters allowing a direct comparison between these results and previous results where cooling was ignored. An immediate assessment can be made concerning the significance of cooling, and if cooling effects need be included in the design analysis.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):254-261. doi:10.1115/1.3453059.

An infrared technique has been used to determine the effects of load, speed and surface roughness on temperature in a sliding EHD point contact. Ball surface temperatures are reported for sliding speeds of 0.35 to 5.08 m/s at 0.52 to 2.03 GN/m2 maximum pressure with surface roughness in the range 0.01 to 0.38 μm c.1.a. The relationship between asperity interaction, as measured by relocation surface profilimetry and high frequency temperature measurements, and the ratio of film thickness to surface roughness has also been studied.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):264-275. doi:10.1115/1.3453074.

Utilizing the theory developed by the authors in an earlier publication, the influence of the ellipticity parameter, the dimensionless speed, load, and material parameters on minimum film thickness was investigated. The ellipticity parameter was varied from one (a ball on a plate configuration) to eight (a configuration approaching a line contact). The dimensionless speed parameter was varied over a range of nearly two orders of magnitude. The dimensionless load parameter was varied over a range of one order of magnitude. Conditions corresponding to the use of solid materials of bronze, steel, and silicon nitride and lubricants of paraffinic and naphthenic mineral oils were considered in obtaining the exponent in the dimensionless material parameter. Thirty-four different cases were used in obtaining the minimum film thickness formula given below as

min=3.63U0.68G0.49W−0.073(1−e−0.68k)
A simplified expression for the ellipticity parameter was found where
k = 1.03RyRx0.64
Contour plots were also shown which indicate in detail the pressure spike and two side lobes in which the minimum film thickness occurs. These theoretical solutions of film thickness have all the essential features of the previously reported experimental observations based upon optical interferometry.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):277-283. doi:10.1115/1.3453077.

Two dimensional Fourier transform methods developed by Ling to calculate contact temperatures were applied to the case of a dry bearing operating with a plastic liner. Results show that uncertainties concerning heat distribution along the contact arc cause smaller differences in contact temperatures than some apparently minor design changes. The effect on temperature of various parameters such as liner position, liner thickness, types of motion and speed, and cooling conditions is given. The method proves to be valuable as a guide in the design of dry bearings.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):284-287. doi:10.1115/1.3453078.

The classical differential equations of motion of the ball mass center in an angular contact thrust loaded ball bearing are integrated with prescribed initial conditions in order to simulate the natural high frequency vibrational characteristics of the general motion. Two distinct frequencies are identified in the analytical simulation and their existence is also confirmed experimentally. One of the frequencies is found to be associated with the Hertzian contact spring at the ball race contact and it is therefore defined as the “elastic contact frequency”, Ωe . The other dominant frequency corresponding to oscillatory motion of the ball in the raceway groove appears to be kinematic in nature and it is, therefore, termed as the “bearing kinematic frequency”, Ωk . It is shown that for a given bearing Ωe and Ωk , vary as, respectively, 1/6 and 1/2 powers of the ball contact load and, therefore, for a given load these frequencies correspond to the natural frequencies of the bearing as applied in any vibrational analysis or simulation.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):290-293. doi:10.1115/1.3453082.

Previous research has established that the laser beam diffraction method can be used for measurement of film thicknesses between two adjacent flat surfaces. This paper describes further experimentation on this method, where oil film thicknesses between rollers is measured. Calibration curves are obtained between the experimental (set) gap and the gap dimensions which are deduced from the diffraction patterns when the laser beam is passed through the film. These set versus calculated film thickness curves are extremely linear for films which are less than 1 mm depth, the coefficients of correlation with straight lines being close to unity. Data based upon several oils used with 76.2 mm dia rollers are presented and empirical equations established. These equations allow the researcher to obtain the film thickness between the rollers in terms of oil properties (density, viscosity and refractive index) and the geometry of the light beam (wavelength, distance from oil film to diffraction screen, and diffraction pattern bandwidth). The empirical constants in the equations for film thickness appear to apply to specific oil types, and remain the same for each family or group of oil used. The groups used here were SAE 10 through 40, low viscosity index and high viscosity index groups. Oil films from 7.62 × 10−3 mm up to 76.2 × 10−3 mm thickness were measured using this method.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):295-301. doi:10.1115/1.3453085.

The dynamic behavior of an externally pressurized porous gas journal bearing is analyzed by assuming one dimensional flow through porous wall. A periodic (displacement) disturbance is imposed on the bearing, and the dynamic pressure distribution is determined by small perturbations of the Reynolds equation. Stiffness and damping for various design conditions are calculated numerically using a digital computer and presented in the form of design charts and tables.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):178-179. doi:10.1115/1.3453009.
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Abstract
Topics: Bearings , Disks
J. of Lubrication Tech. 1977;99(2):244-245. doi:10.1115/1.3453043.
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Abstract
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):245-246. doi:10.1115/1.3453049.
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Abstract
Commentary by Dr. Valentin Fuster

ERRATA

TECHNICAL BRIEFS

J. of Lubrication Tech. 1977;99(2):302-303. doi:10.1115/1.3453086.

Copper specimens whose temperature was varied from room temperature to 500°C were eroded by sand particles. The amount of metal removed increased monotonically over this temperature range except for temperatures between 350 and 425°C. Within this temperature band the erosive action prevented spalling, and thus had a beneficial effect in reducing the overall material removal rate.

Commentary by Dr. Valentin Fuster

BOOK REVIEWS

J. of Lubrication Tech. 1977;99(2):304. doi:10.1115/1.3453087.
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Abstract
Topics: Metrology
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):304-305. doi:10.1115/1.3453088.
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Abstract
Topics: Lubrication
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):305. doi:10.1115/1.3453089.
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Abstract
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1977;99(2):305-306. doi:10.1115/1.3453090.
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Abstract
Topics: Tribology
Commentary by Dr. Valentin Fuster

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