ASME International
0022-2305
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Các bài báo tiêu biểu
Isothermal Elastohydrodynamic Lubrication of Point Contacts: Part III—Fully Flooded Results 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 H¯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.
Tập 99 Số 2 - Trang 264-275 - 1977
Analysis of Gas-Lubricated Foil Journal Bearings This work is concerned with an evaluation of the performance of a gas journal bearing using a spring supported compliant foil as the bearing surface. The analysis, conducted for both single and multipad configurations, is concerned with the effects that the various structural, geometric, and operational variables have on bearing behavior. Following the solution of the relevant differential equation, tabular or graphical solutions are provided for a range of relevant geometric and operational parameters. The solutions include values of the colinear and cross-coupled spring coefficients due to both structural and hydrodynamic stiffness. Desirable design features with regard to start of bearing arc, selection of load angle, number of pads and degree of compliance are discussed.
Tập 105 Số 4 - Trang 647-655 - 1983
A Bulk-Flow Theory for Turbulence in Lubricant Films The purpose of this study on the turbulent lubricant film is: 1 To give a brief outline of a new theory called bulk-flow theory; 2 To investigate to what extent results of theories based on law of wall and mixing length concept agree with the newly developed theory; 3 To provide a theoretical basis for the design of bearings lubricated by fluids of low kinematic viscosity.
Tập 95 Số 2 - Trang 137-145 - 1973
Elastohydrodynamic Lubrication of Elliptical Contacts for Materials of Low Elastic Modulus I—Fully Flooded Conjunction Our earlier studies of elastohydrodynamic lubrication of conjunctions of elliptical form are applied to the particular and interesting situation exhibited by materials of low elastic modulus. By modifying the procedures we outlined in an earlier publication, the influence of the ellipticity parameter k and the dimensionless speed U, load W, and material G parameters on minimum film thickness for these materials has been investigated. The ellipticity parameter was varied from 1 (a ball-on-plate configuration) to 12 (a configuration approaching a line contact). The dimensionless speed and load parameters were varied by 1 order of magnitude. Seventeen different cases were used to generate the following minimum- and central-film-thickness relations: H˜min=7.43(1−0.85e−0.31k)U0.65W−0.21H˜c=7.32(1−0.72e−0.28k)U0.64W−0.22 Contour plots are presented that illustrate in detail the pressure distribution and film thickness in the conjunction.
Tập 100 Số 2 - Trang 236-245 - 1978
Calculation of Stiffness and Damping Properties of Gas Bearings The dynamic characteristics of a gas bearing can be represented by a set of spring and damping coefficients (impedances) which are functions of the static load on the bearing, the rotating speed and the whirl frequency of the journal. For a rotor supported in gas bearings, these coefficients can be used directly in a critical speed calculation or an unbalance response calculation. In addition, the coefficients can be employed in a stability investigation. The paper gives the computational method for obtaining the spring and damping coefficients and, also, describes how they are used in rotor calculations and stability studies. Numerical results are given in graphical and tabular form for a tilting pad journal bearing and a three-lobe journal bearing.
Tập 90 Số 4 - Trang 793-803 - 1968
Dynamics of Rolling-Element Bearings—Part III: Ball Bearing Analysis An analytical formulation for the generalized ball, cage, and race motion in a ball bearing is presented in terms of the classical differential equations of motion. Ball-race interaction is analyzed in detail and the resulting force and moment vectors are determined. The ball-cage and race-cage interactions are considered to be either hydrodynamic or metallic and a critical film thickness defines the transition between the two regimes. Simplified treatments for the drag and churning losses are also included to complete a rigorous analytical development for the real-time simulation of the dynamic performance of ball bearings.
Tập 101 Số 3 - Trang 312-318 - 1979
Piston Ring Lubrication and Cylinder Bore Wear Analysis, Part I—Theory An analytical method developed for determining the bore wear pattern for a reciprocating piston engine over a complete running cycle is presented. The method includes the considerations of the hydrodynamic lubrication theory between the ring and the cylinder bore wall, piston ring geometric and elastic characteristics, blowby through the piston ring pack, minimum film thickness permitting film lubrication, piston side thrust load and Archard’s wear relation. Since the method is general, it also can be applied to other reciprocating piston devices, such as gas compressor, Rankine cycle engine or Stirling engine. Wear factor data, however, must be available in order to make quantitative predictions of wear. The verification of the present theory is given in a subsequent paper (Part II) which shows good agreement between the predicted bore wear curves and measured ones for actual engines.
Tập 96 Số 3 - Trang 305-313 - 1974
An Analytical Method to Predict Skidding in Thrust-Loaded, Angular-Contact Ball Bearings
Tập 93 Số 1 - Trang 17-23 - 1971
Dynamics of Rolling-Element Bearings—Part IV: Ball Bearing Results Dynamic simulations of the performance of a ball bearing are presented in terms of the general motion as obtained by integrating the differential equations of motion of the various bearing elements. It is shown that bearing misalignment significantly influences the ball/cage and race/cage interaction and, hence, the stability of cage motion. The increased radial to axial load ratios promote skidding which couples with the lubricant behavior to impose accelerations on the ball which ultimately influence the ball/cage interactions. Hence, the lubricant behavior and the large load variation on the balls play dominant roles not only in determining the extent of skidding but also in establishing the overall stability of the cage motion.
Tập 101 Số 3 - Trang 319-326 - 1979