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Showing papers in "Tribology Transactions in 1975"


Journal ArticleDOI
TL;DR: In this article, the authors conducted bench decomposition studies on three commercial ZDP's in which the effects of oxygen, water, other additives in the blend, and the base oil were investigated.
Abstract: Despite the widespread use of zinc organodithiophosphates (ZDP's) as antiwear additives, how the ZDP's perform their antiwear function is still vague. Thermal decomposition of ZDP's and the formation of a protective antiwear coating by the decomposition products is one popular theory; but the correlation between thermal decomposition temperature and antiwear performance leaves something to be desired. To determine if other factors influence ZDP behavior, bench decomposition studies were conducted on three commercial ZDP's in which the effects of oxygen, water, other additives in the blend, and the base oil were investigated. For these studies, the bulk oil changes were followed by infrared spectroscopy, volatiles formation by pressure measurements, solids formation by centrifugation and subsequent elemental analysis and surface coating formation on steel balls by x-ray fluorescence spectroscopy. It was found that the decomposition of ZDP's is affected by oxygen availability, water, other additives in the ...

76 citations


Journal ArticleDOI
TL;DR: In this paper, the friction and wear properties of various carbons and graphites have been measured during sliding against themselves in air and the sliding conditions at the transition are associated with a critical temperature of the contacting asperities, and the magnitude of this temperature, approximately 150-185 C for graphitic materials, has been estimated both directly and by application of flash-temperature theory.
Abstract: The friction and wear properties of various carbons and graphites have been measured during sliding against themselves in air. Many materials exhibit sudden and large increases in both friction and wear at a critical combination of load, speed, and temperature, and the effects are most pronounced for electrographites and natural graphites. The sliding conditions at the transition are associated with a critical temperature of the contacting asperities, and the magnitude of this temperature, approximately 150–185 C for graphitic materials, has been estimated both directly and by application of flash-temperature theory. The phenomena accompanying the transitions are very similar to those occurring during dusting of carbon brushes at high altitudes, and a similar explanation is invoked in terms of the adsorption of water vapor and oxygen. The critical combinations of loads and speeds required to initiate the transition are much more severe than those normally encountered during the operation of carbon brushes...

75 citations


Journal ArticleDOI
TL;DR: In this article, a capillary viscometer was used to measure viscosity as a function of pressure, temperature, and shear stress for a number of lubricants.
Abstract: A capillary viscometer was used to measure viscosity as a function of pressure, temperature, and shear stress for a number of lubricants. Measurements were made at 38 C, 99 C, and 149 C (100 F, 210 F, and 300 F), gauge pressure to 5.5 × 108 N/m2 (8 × 104 psi), and shear stresses to 106 N/m2 (14.5 psi). At 38 C (100 F), the order of the pressure-viscosity coefficients for the unformulated fluids was: fluorinated polyether > synthetic hydrocarbon > naphthenic mineral oil > synthetic paraffinic oil (lot 4) > C-ether ≅ synthetic paraffinic oil (lot 3) > polyalkyl aromatic > advanced ester. All pressure viscosity coefficients decreased with increasing temperature. Fair agreement was obtained when pressure-viscosity coefficients at 38 C (100 F) and 6.9 × 107 N/m2 (104 psi) were compared to data from other investigators using different techniques (optical elastohydrodynamics, oscillating crystal, and low shear capillary viscometry). Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME...

73 citations


Journal ArticleDOI
TL;DR: In this paper, a method for calculating the pressure distribution, film profile, leakage rate and friction of a rectangular section rubber seal as used in hydraulic rams and jacks is described.
Abstract: This paper describes a method for calculating the pressure distribution, film profile, leakage rate and friction of a rectangular section rubber seal as used in hydraulic rams and jacks. The two basic equations, those describing the hydrodynamic pressure generation and the deflections of the seal surface have been solved simultaneously by numerical techniques. A solution was obtained which predicted film profiles qualitatively similar to those obtained experimentally. Solutions for outstrokes were obtained over ranges of variables as follows: sealed pressure (lbf/in2)…200–1,500500500sliding speed (ft/min)….150.5–25.015rubber hardness (IRHD).858555–85 Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974

64 citations


Journal ArticleDOI
TL;DR: In this article, a statistical expression for the fractional reduction in fatigue life at full film conditions due to the competition between asperity induced fatigue and fatigue due to indigenous surface defects and subsurface inclusions is presented.
Abstract: A statistical expression, showing as a function of the film parameter (film thickness/surface roughness or h/σ) the fractional reduction in fatigue life at “full film” conditions due to the competition between asperity induced fatigue and fatigue due to indigenous surface defects and subsurface inclusions, is presented. Several sources of endurance test data relating the fatigue life of a rolling bearing to the film parameter are reviewed. To unify the experimental data a “relative” fatigue life raised to the power of e, the Weibull dispersion parameter, is plotted against the film parameter. Comparisons between the theoretical and experimental results are then made which reveal that the increase in bearing fatigue life due to the film parameter can be described by the theoretical model with a “reference” film parameter value of 1.5 for h/σ > 0.5. For h/σ < 0.5, the variation of h/σ explains only a minor portion of the scatter of the fatigue lives. Presented at the 29th Annual Meeting in Cleveland, Ohio, ...

61 citations


Journal ArticleDOI
TL;DR: In this article, the authors discuss magnetic fluids: what are they, what are their intrinsic properties, and how can they be controlled and positioned to create zero-leakage, nonwearing ferrofluidic seals.
Abstract: If a lip seal could use a liquid lip, the resulting perfect conformity to the rotating and stationary surfaces would negate the effects of surface finish and mechanical run-out Magnetic fluids, called ferrofluids, make this type of seal possible and practical This paper discusses magnetic fluids: what are they, what are their intrinsic properties, and how can they be controlled and positioned to create zero-leakage, nonwearing ferrofluidic seals Design parameters of ferrofluidic seals including radial gap, differential pressure, rotary speed and torque are developed Specific examples of hard-vacuum, exclusion and rotating-machinery applications illustrate the versatility of magnetic-liquid seals, which have been used primarily for gas service Other potential seal applications include packings, face seals, and conventional lip seals which can benefit from use of newly developed magnetic-fluid lubricants Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974

56 citations


Journal ArticleDOI
TL;DR: In this paper, a series of organic disulfides and two dialkyldithiophosphates were used to identify surface layers produced on En31 (A1SI 52100) steel specimens by wear tests.
Abstract: Glancing angle X-ray diffraction, electron probe micro-analysis, scanning electron microscopy, and optical microscopy combined with sectioning and microhardness testing, have been used to identify surface layers produced on En31 (A1SI 52100) steel specimens by a series of organic disulfides and two dialkyldithiophosphates in wear tests. It is shown that the combined use of these techniques gives much more information than the use of any single one. The findings are discussed in relation to current theories of the action of extreme pressure lubricants. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

52 citations


Journal ArticleDOI
TL;DR: In this paper, an experiment was conducted to examine the independent influences of rolling speed and sliding speed on the scuffing of hardened steel discs lubricated by a mineral oil, and it was shown that both sliding speed and rolling speed have important effects on scuffings conditions.
Abstract: An experiment has been conducted to examine the independent influences of rolling speed and sliding speed on the scuffing of hardened steel discs lubricated by a mineral oil. Both sliding speed and rolling speed have important effects on the scuffing conditions. There is a difference between scuffing conditions at low mean rolling speeds, 0.8 m s−1 or less, and those at higher rolling speeds, 1.6 m s−1 or above. Various criteria for scuffing have been examined. It is possible to define ranges of rolling and sliding speeds over which any one of three of these criteria, total contact temperature, film thickness and friction power intensity, is approximately constant. All these quantities show wide variations outside their respective ranges. Of these criteria, the friction power intensity has the widest range of application. Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974

42 citations


Journal ArticleDOI
TL;DR: In this paper, a series of tests has been conducted to evaluate the suitability of silicon nitride as a bearing material for rolling contact applications, which was determined by wettability studies, lubricant film thickness and traction coefficient measurements on the optical EHD rig and friction coefficient measurements by the pin-on-disk method.
Abstract: A series of tests has been conducted to evaluate the suitability of silicon nitride as a bearing material for rolling contact applications. The ability of silicon nitride to be lubricated by some conventional lubricants was found to be satisfactory. This was determined by wettability studies, lubricant film thickness and traction coefficient measurements on the optical EHD rig and friction coefficient measurements by the pin-on-disk method. The abrasive wear coefficient, measured on a lopping machine using 600 grit SiC abrasive, was found to be high compared to other ceramics. It was also dependent on the composition of the silicon nitride. Comparative rolling contact fatigue tests on steel and silicon nitride flat washers were conducted using steel rollers and balls. A high wear rate leading to grooving in the rolling track on silicon nitride was observed. The spalling resistance of silicon nitride was found to be higher than that of steel under the test conditions used. Surface interactions in the Si3N4...

33 citations


Journal ArticleDOI
TL;DR: In this paper, the types of wear particles generated by a five-ring polyphenyl ether in boundary lubrication experiments in various atmospheres were determined by ferrographic analysis.
Abstract: The types of wear particles generated by a five-ring polyphenyl ether in boundary lubrication experiments in various atmospheres were determined by ferrographic analysis. The types of wear particles observed included cylindrical or rocklike organometallic debris, adhesive and cutting wear particles, and some spherical debris. Interpretations as to the mechanism of generation of the various types of particles are presented.

25 citations


Journal ArticleDOI
TL;DR: In this article, a model for mixed lubrication is presented, where the surface asperities are represented by short plasto-elastic cylinders with spherical tops, and the heights of these cylinders are assumed to have a Gaussian distribution.
Abstract: This paper presents a model for mixed lubrication. The surface asperities are represented by short plasto-elastic cylinders with spherical tops. The heights of these cylinders are assumed to have a Gaussian distribution. By combining the solution of the Reynolds equation and the solution from boundary lubrication theory or the microelastohydrodynamic lubrication theory, the load and friction of the lubricated contact can be calculated. Three calculated examples which showed the essential characters and interesting results of mixed lubrication were given. The correlation with others' experimental results was reasonably good.

Journal ArticleDOI
TL;DR: In this paper, the authors present a description of recently developed high pressure light scattering techniques which for the first time make an extensive study of the pressure and temperature dependence of the viscoelastic properties of lubricants feasible.
Abstract: Recent investigations of EHD lubrication have indicated the importance of viscoelastic properties in explaining the differences in the behavior of different lubricants. Up to the present time, however, very little of the data necessary to develop a reliable viscoelastic model of EHD lubrication has been available. It is the purpose of this article to present a description of recently developed high pressure light scattering techniques which for the first time make an extensive study of the pressure and temperature dependence of the viscoelastic properties of lubricants feasible. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

Journal ArticleDOI
Rüdiger Holinski1
TL;DR: In this article, an American Society of Lubrication Engineers paper at the ASLE/ASME Conference held in Montreal, Canada, October 8-10, 1974 was presented.
Abstract: Metal surfaces have been investigated after lubrication tests with oils containing solid lubricants. With an MoS2-containing engine oil, an MoS2-film was formed on engine parts. Solids without a layer structure also formed solid films on metal surfaces at the area of frictional contact. These films are, however, not the original compounds, but products of chemical reaction. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

Journal ArticleDOI
TL;DR: In this paper, a fracture mechanics technique has been used to determine the rate of fatigue crack propagation in rotating-beam SAE 52100 steel specimens in several lubricating environments, including water-in-oil emulsion, distilled water, and air.
Abstract: A fracture mechanics technique has been used to determine the rate of fatigue crack propagation in rotating-beam SAE 52100 steel specimens in several lubricating environments. Experiments were conducted in a mineral and antiwear hydraulic oil under wet and dry conditions, a water-in-oil emulsion, distilled water, and air. Differences as high as 8:1 in crack propagation rates were observed among these environments; the differences were found to depend on the magnitude of the stress-intensity factor at the crack tip. A method is outlined for separating the crack initiation stage from the propagation stage in rotating-beam specimens. This method is expected to provide new insights regarding the chemical influence of lubricants on the mechanisms responsible for fatigue crack development in bearings. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

Journal ArticleDOI
TL;DR: In this article, an optical interference method was used to display the distorted film shape in nominally parallel surface thrust washers and an analysis of the coupled elasticity, Reynolds and energy equations confirm that these bearings operate by the formation of a slightly converging film over the leading 80 percent (or less) of the pad.
Abstract: An optical interference method was used to display the distorted film shape in nominally parallel surface thrust washers. The bearings were made of aluminium to accentuate thermal expansion and were carefully lapped flat before use. Both the experimental results and an analysis of the coupled elasticity, Reynolds and energy equations confirm that these bearings operate by the formation of a slightly converging film over the leading 80 percent (or less) of the pad. Fair agreement was obtained between the analysis and previously developed multiple regression equations. Thrust washers for industrial use with random waviness are likely lo perform better than lapped bearings. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

Journal ArticleDOI
TL;DR: In this paper, the results of scuffing tests performed with carburized AISI 9310 steel disks and a MIL-L-7808G oil, at a variety of sliding and sum velocities, and with disks ground both axially and circumferentially but with the same composite surface roughness are presented.
Abstract: This paper presents the results of scuffing tests performed with carburized AISI 9310 steel disks and a MIL-L-7808G oil, at a variety of sliding and sum velocities, and with disks ground both axially and circumferentially but with the same composite surface roughness. On the basis of these results, a methodology for correlating and predicting the thermal and scuffing behavior of sliding-rolling disks is suggested. It is demonstrated that the difference between the oil-film temperature at the conjunction inlet and the oil jet temperature, as well as the difference between the disk surface temperature and the oil jet temperature, are basically related to the frictional power loss at the sliding-rolling contact. The scuffing failure results are examined and compared by three different criteria: the critical temperature, the critical frictional power, and the critical frictional power intensity. It is shown that under certain operating conditions the critical temperature and critical frictional power intensit...

Journal ArticleDOI
TL;DR: In this paper, a cam-operated single cylinder pump was used to test several pump material combinations using two chemically different hydraulic fluids and the main parameters monitored were the degree of mutual electrical insulation attained and the physical drag of the piston on the cylinder due to both viscous shear and asperity interaction.
Abstract: Conventional high-pressure hydraulic piston pumps require a delicate balance between clearance, surface finish, and pump materials if a long, efficient life is to be maintained. A cam-operated single cylinder pump has been used to test several pump material combinations using two chemically different hydraulic fluids. The main parameters monitored were the degree of mutual electrical insulation attained and the physical drag of the piston on the cylinder due to both viscous shear and asperity interaction. It was found that for hardened steel pistons and cylinders an optimum surface finish of approximately 8 μinches CLA gave the best results with both fluids. Results are explained on the basis of micro-asperity hydrodynamic lift. Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974

Journal ArticleDOI
TL;DR: In this article, a spiral bevel pair is used to measure the surface temperature of a gear tooth using an EP oil and the history of a score/recovery mechanism.
Abstract: Work in the field of gear tooth surface distress during recent years has shown clearly that surface temperature history provides the key to performance predictions. This especially applies when using an EP oil. Many attempts have been made to monitor surface temperature by using a variety of thermocouple designs. None of these attempts has resulted in the developing of a practical tool and all interfere with the surface continuity and can initiate scoring. An infra-red technique offered a satisfactory solution to this temperature measurement problem if the complexities of calibration could be resolved. This paper describes how a satisfactory technique was evolved along with results of proving tests when applied to a spiral bevel pair. Also included is the surface temperature history of a score/recovery mechanism. A practical tool for the measurement of gear tooth surface temperature has been developed and, slightly modified, the same technique is now being applied to temperature measurements within a roll...

Journal ArticleDOI
TL;DR: In this paper, the frequency and amplitude of axial vibration along with pressure distributions, friction torque, and leakage values are calculated for a radial face seal operating under a constant closure load.
Abstract: It is known theoretically and has been proved experimentally that, if both faces of a radial face seal, operating under a constant closure load, are misaligned, an axial vibration will occur. The frequency and amplitude of this vibration along with pressure distributions, friction torque, and leakage values are calculated here. Results show that a 4 to 1 increase in misalignment angle will cause the friction to drop by 20 percent, the leakage to increase by 100 percent, and the vibration amplitude to increase by 30 percent. This study will be extended to include other “surface defects” such as waviness. On the more fundamental side, flow considerations around the cavitation zone lead us to question the validity of the oil rheology model commonly used under actual working conditions. Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974

Journal ArticleDOI
P. A. Engel1, J. L. Sirico1
TL;DR: In this paper, the rate process of wear with respect to the impact parameters (normal and tangential approach velocity), and lubricant viscosity was investigated with a pivotal hammer type impact testers.
Abstract: Pivotal hammer type impact testers are used in an experimental study of repetitively impacted lubricated contacts. Various steels are used in one- and two-body wear modes; the rate process of wear is investigated with respect to the impact parameters (normal and tangential approach velocity), and lubricant viscosity. For normal impact, a boundary lubrication system forms, but superimposed sliding speeds with a viscous lubricant tend to create an elastohydrodynamic lubrication (EHL) condition, greatly resisting wear. Approximate measurable wear equations are derived for cylindrical striking surfaces. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

Journal ArticleDOI
TL;DR: In this paper, a new optical EHD machine is described which allows traction to be applied while measuring the film thickness, and a range of 13 pure fluids with well characterized physical properties was studied.
Abstract: A new optical EHD machine is described which allows traction to be applied while measuring the film thickness. A range of 13 pure fluids with well characterized physical properties was studied. A convenient way of plotting friction coefficient f against slide/roll ratio Σ was found to be log (1 - f/fmax)˜Σ as linear plots are achieved. The value of the peak friction coefficient fmax varied between 0.011 and 0.09. The glass transition temperature gave the best correlation with this, though not a very satisfactory one, and the pressure viscosity coefficient was next best. Presented at an American Society of Lubrication Engineer paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

Journal ArticleDOI
TL;DR: A series of soluble metal phenoxides prepared from two phenols was investigated as high-temperature (to 371 C) anti-oxidants in polyphenyl ether (5P4E) as discussed by the authors.
Abstract: A series of soluble metal phenoxides prepared from two phenols was investigated as high-temperature (to 371 C) anti-oxidants in polyphenyl ether (5P4E). Compounds from Group 1A (alkalis) and 2A (alkaline earths) were effective, but not in the same order as their inorganic oxide, hydroxide and carbonate counterparts studied earlier. High-temperature antioxidant activity of the phenoxides was not adversely affected by water-saturated air; the phenoxides were, however, subject to hydrolysis at 40 C by persistent exposure to liquid water. The phenoxides did not adversely affect the pyrolytic stability of the ether in the absence of air, although they were themselves slightly degraded. Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974

Journal ArticleDOI
TL;DR: In this article, the friction-temperature characteristics of a series of lubricated copper-tin solid solutions were investigated on a modified four-ball machine, and the average tin contents (within the depth penetrated by the probe) appeared to control the values of the heats of adsorption.
Abstract: The friction-temperature characteristics of a series of lubricated copper-tin solid solutions are investigated on a modified four-ball machine. Heats of adsorption of the polar component of the lubricant onto the alloy surfaces are measured by a critical temperature method. These are not found to be a simple function of the bulk tin content of the alloys as would be expected intuitively. Electron probe microanalysis of the wear scars of the alloys reveals that tin atoms migrate towards the worn surfaces during the friction tests, most probably by an interaction with dislocations. The average tin contents (within the depth penetrated by the probe) appear to control the values of the heats of adsorption. It is suggested that, in many cases, bulk compositions should not be expected to hold near worn surfaces. Presented at an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

Journal ArticleDOI
TL;DR: In this paper, a model is presented to predict the maximum frequency attainable for a typical noncontacting face seal (for gas service) to be run successfully in the presence of axial runoul.
Abstract: A model is presented here to predict the maximum frequency attainable for a typical noncontacting face seal (for gas service) to be run successfully in the presence of axial runoul. This work has been carried out because the determination of maximum allowable speed by laboratory testing results in serious and costly damage to seal rings. The circumferential variation in gas film thickness, spring load, seal gas pressure, and seal geometry are considered in estimating the applied torque to the stator enabling it to dynamically track the misaligned rotor. The mathematical expression arrived at shows that, for a fixed seal geometry, the maximum frequency is proportional to the square root of the closing force and inversely proportional to the square root of both axial runoul and mass. Calculations and laboratory experience available for testing the model, though very limited, are in reasonable agreement. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference h...

Journal ArticleDOI
TL;DR: A new ball fatigue tester, the Twin-Head Five-Ball Machine, developed in order to study the effect of traction and sliding on fatigue life, is described in detail.
Abstract: A new ball fatigue tester, the Twin-Head Five-Ball Machine, developed in order to study the effect of traction and sliding on fatigue life, is described in detail. The novel features offered by the apparatus are presented and their implications discused. Three groups of balls were tested with a synthetic diester oil, at a constant maximum Hertz stress of 6GN m−2 (875,000 psi) in pure rolling and at two levels of sliding and traction. Results show a significant decrease in life for a small level of sliding or traction. Life appears to be better correlated to traction coefficient than to sliding. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

Journal ArticleDOI
TL;DR: In this article, the oscillating quartz crystal viscometer has been used to investigate possible viscoelastic behavior in synthetic lubricating fluids and to obtain viscosity-pressure-temperature data for these fluids at temperatures to 300 F and pressures to 40,000 psig.
Abstract: The oscillating quartz crystal viscometer has been used to investigate possible viscoelastic behavior in synthetic lubricating fluids and to obtain viscosity-pressure-temperature data for these fluids at temperatures to 300 F and pressures to 40,000 psig. The effect of pressure and temperature on the density of the test fluids was measured concurrently with the viscosity measurements. Viscoelastic behavior of one fluid, di-(2-ethylhexyl) sebacate, was observed over a range of pressures. These data were used to compute the reduced shear elastic (storage) modulus and reduced loss modulus for this fluid at atmospheric pressure and 100 F as functions of reduced frequency.

Journal ArticleDOI
TL;DR: In this paper, a force analysis of the Falex configuration was performed to determine the compressive stresses in the contact zones at the time of lubricant failure, and wear scar variations were found between sides of the same vee block and between vee blocks from the same test.
Abstract: Two sets of Falex test specimens were examined to determine the compressive stresses in the contact zones at the time of lubricant failure. Two wear scar variations were found: (1) between sides of the same vee block, and (2) between vee blocks from the same test. To explain these anomalies, a force analysis of the Falex configuration was made. The force analysis of a vee block revealed that the two faces have the same normal loads only when there is no motion. Details and force curves are presented. The force analysis of the lever system revealed that only if the two halves of the lever system were identical (with manufacturing tolerances identical) would the loading on the two vee blocks in a single test be the same. Conclusions relative to the analysis and final compressive stress results are made. Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974

Journal ArticleDOI
TL;DR: In this article, a method of successive approximations for calculating lubricant film pressures in plane bearings under the combined action of hydrodynamic and hydrostatic lubrication is described, and the accuracy and convergence of the method are discussed.
Abstract: The paper describes a method of successive approximations for calculating lubricant film pressures in plane bearings under the combined action of hydrodynamic and hydrostatic lubrication. Successive iterations are obtained through redefinition of the boundary pressures. The accuracy and convergence of the method are discussed.

Journal ArticleDOI
TL;DR: In this article, a numerical analysis is presented which takes into consideration both the nonlinear and frictional effects, showing that frictional forces can become significant at large deflections and cause an increase in the measured strength.
Abstract: In testing high strength, elastic materials by the four-point bending method, large deflections can occur. Under these conditions the relationship between load and deflection becomes nonlinear and analyses of results based on simple beam theory may lead to serious errors. Furthermore, friction between the test piece and supports can have an important effect on the results. A numerical analysis is presented which takes into consideration both the nonlinear and frictional effects. The analysis shows that frictional forces can become significant at large deflections and cause an increase in the measured strength. Experimental evidence is given to support these analytical results. Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974

Journal ArticleDOI
TL;DR: An elastodynamic stress and deformation analysis for the hollow ball is given in this paper, and a computer program for the stress analysis, though not part of the paper, is available upon request.
Abstract: An elastodynamic stress and deformation analysis for the hollow ball is given. A computer program for the stress analysis, though not part of the paper, is available upon request. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974