0


REPORTS

J. of Lubrication Tech. 1976;98(2):193-195. doi:10.1115/1.3452790.
FREE TO VIEW
Abstract
Topics: Lubrication
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):317-318. doi:10.1115/1.3452837.
FREE TO VIEW
Abstract
Topics: Fatigue
Commentary by Dr. Valentin Fuster

RESEARCH PAPERS

J. of Lubrication Tech. 1976;98(2):196-204. doi:10.1115/1.3452791.

The mobility-whirl angle method as introduced by Booker in 1964, has been applied to pivoted pad journal bearings to predict the behavior of a rotor supported in this type of bearing. Both the single pivoted pad and the complete radial bearing with three equally spaced radial pads have been analyzed. It will be shown that the method is restricted to the case where the value of the load on each pad has to be known from the start. Some experiments have been carried out on a squeeze apparatus. The results are in reasonable agreement with numerical results.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):206-213. doi:10.1115/1.3452795.

The paper presents the results of an experimental investigation in which the damping coefficients of a squeeze-film bearing are obtained from impedance measurements. For various force levels, and for frequencies up to 200 Hz, the bearing length, radial clearance, and viscosity are varied and both the concentric and the eccentric case are investigated. Good correlation is found with a simplified linearized theory for moderate force levels, and for higher force levels the correlation is satisfactory when the oil supply pressure is increased sufficiently.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):214-222. doi:10.1115/1.3452798.

The general hydrodynamic behavior at small clearance Reynolds numbers of two fluids of different density and viscosity occupying the finite annular space between a rotating and stationary disk is explored using a simplified version of the Navier-Stokes equations which retains only the centrifugal force portion of the inertia terms. A criterion for selecting the annular flow fields that are compatible with physical reservoirs is established and then used to determine the conditions under which two-fluid flows in the annulus might be expected for specific fluid combinations.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):223-228. doi:10.1115/1.3452801.

The analysis of an isothermal elastohydrodynamic lubrication (EHL) point contact was evaluated numerically. This required the simultaneous solution of the elasticity and Reynolds equations. In the elasticity analysis the contact zone is divided into equal rectangular areas and it is assumed that a uniform pressure is applied over each element. In the numerical analysis of the Reynolds’ equation a phi analysis where phi is equal to the pressure times the film thickness to the 3/2 power is used to help the relaxation process. The EHL point contact analysis is applicable for the entire range of elliptical parameters and is valid for any combination of rolling and sliding within the contact.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):230-235. doi:10.1115/1.3452805.

A small diamond disk mounted as a window in a steel plate was covered with test fluid, and a weighted steel ball was rotated over the window so as to form a sliding elastohydrodynamic (EHD) contact region. Some of the radiant energy generated in this region, both in the fluid and at the boundaries, passed through the window into an infrared interferometer, giving rise to an emission spectrum. This spectrum could be separated into contributions from the fluid and from the ball surface, making it possible, by appropriate calibrations, to estimate their temperatures separately under operating conditions. Moreover, the shape of the discrete spectral bands of the fluid permitted some inferences on its state. Two fluids were studied under identical mechanical conditions, a polyester and a naphthenic oil, each containing an equal amount of polymethylstyrene as a spectral indicator. Differences of band intensity, band width, and frequency could, therefore, be attributed to differences in the behavior of the base fluid. The principal results were much lower fluid temperatures and lower metal surface temperatures when the polyester was used than when the naphthenic oil was similarly used. Polyester films were also thicker and of higher density than naphthenic oil films under the same conditions. This work is only the beginning of a comprehensive study of EHD contacts by infrared spectroscopy, but the results already achieved lead to interesting speculations on the mechanisms of EHD processes, which further study is expected to elucidate.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):236-242. doi:10.1115/1.3452806.

An improved technique for the measurement of temperature distributions in an EHD conjunction is presented. The technique reported here employs the infrared radiation emitted by the EHD conjunction and appears more rigorous, more reliable, and less cumbersome than that reported previously by the authors. Detailed mapping of fluid temperature (averaged through the thickness) and the ball surface temperature can be obtained. These temperature distributions have been reported for a naphthenic mineral oil for peak Hertz pressures of 1.05 and 1.51 GN/m2 (148 and 219 kpsi), at sliding speeds ranging from 0.35 to 12.7 m/s (13.4 to 500 ips) and a bath temperature of 40°C.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):244-248. doi:10.1115/1.3452810.

The paper deals with experimental measurement of bearing torque and “percentage of lubrication” in instrument size (R6) bearings. The primary parameter found to affect bearing performance for several lubricant investigations is base viscosity. Inference of EHD film thickness is made from the percentage of film measurements which are compared with X-ray data. A reasonable correlation between the two types of data is presented, thereby, paving the way toward the use of the more universally applicable percentage of film measurements for the determination of EHD conditions in real bearing systems.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):251-257. doi:10.1115/1.3452814.

In this first part of a two-part paper, a mathematical model is presented for the prediction of spalling fatigue life in rolling bearings, which operate in contaminated lubricant, resulting in denting damage of the rolling surfaces. Five damage accumulation cases are treated: (I) Early or pre-existing damage; (II) Linear damage accumulation from constant lubricant contamination; (III) Accelerating damage from progressive wear; (IV) A combination of the above; and (V) Damage leveling off during stress cycling. Cases (I)-(III) lead to Weibull distributions of fatigue life, the others to more complex distributions. Experimental corroboration and application examples of the model are presented in Part II [16] of this paper.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):258-265. doi:10.1115/1.3452815.
Abstract
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):267-274. doi:10.1115/1.3452819.

A mathematical model for surface fatigue life of gear, pinion, or entire meshing gear train is given. The theory is based on the statistical approach used by Lundberg and Palmgren for rolling-element bearings. Also equations are presented which give the dynamic capacity of the gear set. The dynamic capacity is the transmitted tangential load which gives a 90 percent probability of survival of the gear set for one million pinion revolutions. The analytical results were compared with test data for a set of AISI 9310 spur gears operating at a maximum Hertz stress of 1.71 × 109 N/m2 (248,000 psi) and 10,000 rpm. The theoretical life predictions were very good when material constants obtained from rolling-element bearing tests were used in the gear life model.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):277-284. doi:10.1115/1.3452823.

The instability of two rings in rotating, sliding contact is examined. The configuration is typical of that of a mechanical face seal. Circumferentially varying friction heating at the seal interface may lead to an unstable thermoelastic distortion of the ring and uneven wear. Heat transfer equations are developed which include the effects of contact conductance and unsteady state heat transfer in one of the rings. Deflection equations, which include both thermal and mechanical loading, are developed and combined with a wear equation to form a mathematical model that predicts the limits for stable operation. It is shown that contact conductance, ring stiffness, thermal coefficient of expansion, sliding speed, friction, thermal conductivïty, and geometry are important parameters in relation to stability. Stability conditions are established for several cases. The harmonic content of the uneven wear resulting from instability depends on the initial waviness of the ring and point of operation in the region of instability. It is shown that some seals are stable at all harmonics.

Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):308-315. doi:10.1115/1.3452832.

A brief review of relevant literature is presented with the logic underlying the selection of lubricant base stocks, additives, materials, surface textures, and other variables used in contact fatigue tests under rolling-sliding conditions. Tests of selected combinations (mineral oil with and without a zinc dialkyldithiophosphate additive and a polyolester synthetic with and without its typical additive package) showed that lubricant chemistry affects the stress/life slope and the Weibull slope (scatter in life). Results of the overall program show that the relative contact fatigue life for different lubricant chemistries should be evaluated using operating conditions, especially stress and slip levels, near to expected application conditions.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):319-329. doi:10.1115/1.3452838.

The results of an extensive investigation of the transient response of rotors supported in fluid-film journal bearings is presented in the form of computer generated orbits of rotor motion. The stability of the rotor-bearing system was determined by examination of the system characteristic equation in Part 1. Rotor transient response orbits demonstrate the rotor behavior below and above the stability threshold. The results show the effect of imbalance, steady loading, cyclic unidirectional and rotating loads upon the stability and performance of a short journal bearing. The results are compared to previous investigations and modified stability maps are deduced from the results obtained. The concept of whirl is examined and several plots presented of the instantaneous whirl ratio and radius of curvature versus cycles of motion (of the journal) for the various cases considered. Bearing forces are analyzed and the resulting plots of force versus cycles of motion are presented for selected cases.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):330-333. doi:10.1115/1.3452839.
Abstract
Topics: Wear
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):335-342. doi:10.1115/1.3452842.

The paper presents a theoretical analysis of hydrodynamic lubrication in the hydrostatic extrusion process which includes a consideration of thermal effects in the lubricant film arising from the work of plastic deformation. A Newtonian lubricant with an exponential pressure-temperature-viscosity relationship has been assumed and allowance has been made for the effects of redundant deformation of the worked material. The results of the theory are compared with those from previous isothermal and solid friction theories.

Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):344-347. doi:10.1115/1.3452846.

The flow through a narrow channel with a flexible wall is analyzed. In this problem the inlet width of the channel is prescribed by a guide but the distribution of channel width is not a priori known. The paper presents the results of the two flow models and compares them to experimental values.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):334. doi:10.1115/1.3452840.
FREE TO VIEW
Abstract
Topics: Wear
Commentary by Dr. Valentin Fuster
J. of Lubrication Tech. 1976;98(2):334. doi:10.1115/1.3452841.
FREE TO VIEW
Abstract
Topics: Wear
Commentary by Dr. Valentin Fuster

BOOK REVIEWS

J. of Lubrication Tech. 1976;98(2):349. doi:10.1115/1.3452849.
FREE TO VIEW
Abstract
Commentary by Dr. Valentin Fuster

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In