Stresses in Oil Lubricated Bearings

1969 ◽  
Vol 184 (1) ◽  
pp. 69-82 ◽  
Author(s):  
S. M. Ibrahim ◽  
H. Mccallion
Keyword(s):  
Thrust Bearing ◽  
Journal Bearing ◽  
Fluid Pressure ◽  
Temperature Gradients ◽  
Rigid Surface ◽  
Pressure Loading ◽  
Bearing Surface ◽  
Bearing Ring ◽  
Difference Analogue ◽  
Differential Thermal Expansion

Stresses in a bimetal strip of white metal bonded to steel, to simulate a journal bearing shell or a thrust bearing ring, have been calculated for various loading conditions. The stresses arose from: fluid pressure loading on the bearing surface whilst the back was supported on a complete rigid surface; locating and holding forces, e.g. compression due to nipping-up the bearing; elastic deformation of the bearing housing; differential thermal expansion and temperature gradients, and incomplete support of the bearing shell when subjected to fluid pressure on its bearing surface. Points at which fatigue damage is likely to originate are apparent. The stresses were calculated numerically from displacements which were found, by an iterative method, to satisfy a finite difference analogue of the governing differential equations.

Static and Dynamic Characteristics of Aerostatic Circular Porous Thrust Bearings (Effect of the Shape of the Air Supply Area)

2000 ◽  
Vol 123 (3) ◽  
pp. 501-508 ◽  
Author(s):  
S. Yoshimoto ◽  
K. Kohno
Keyword(s):  
Porous Material ◽  
Dynamic Characteristics ◽  
Thrust Bearing ◽  
Aerostatic Bearing ◽  
Bearing Surface ◽  
Static And Dynamic Characteristics ◽  
Thrust Bearings ◽  
Porous Bearing ◽  
Air Supply ◽  
Bearing Design

Recently, graphite porous material has been used successfully in an aerostatic bearing. In actual bearing design, it is often necessary to reduce the thickness of porous material to make the bearing smaller. However, a reduction in thickness results in a reduction in the strength of the porous material. In particular, when the diameter of porous material is large, it is difficult to supply the air through the full pad area of porous material because it deforms. Therefore, in this paper, two types of air supply method (the annular groove supply and the hole supply) in a circular aerostatic porous thrust bearing are proposed to avoid the deflection of the bearing surface. The static and dynamic characteristics of aerostatic porous bearing with these air supply methods are investigated theoretically and experimentally. In addition, the effects of a surface restricted layer on the characteristics are clarified.

Numerical analysis of the transient wear and lubrication behaviors of misaligned journal bearings caused by linear shaft misalignment

2021 ◽  
pp. 1-17
Author(s):  
Tianyou Yang ◽  
Yanfeng Han ◽  
Yijia Wang ◽  
Guo Xiang
Keyword(s):  
Numerical Model ◽  
Film Thickness ◽  
Contact Pressure ◽  
Elastic Deformation ◽  
Journal Bearing ◽  
Fluid Pressure ◽  
Axial Direction ◽  
Wear Depth ◽  
Wear Process ◽  
Journal Misalignment

Abstract The purpose of this study is to investigate the role of the misalignment journal, caused by journal elastic deformation, on the transient wear and mixed lubrication performances using a numerical model. In the numerical model, the transient geometry lubrication clearance considering the journal misalignment, the transient elastic deformation and the transient wear depth are incorporated to evaluate the transient film thickness during wear process. The evolutions, under different external loads, of the wear depth, wear rate, elastic deformation, film thickness, fluid pressure and contact pressure are calculated by the numerical model. Furthermore, the calculated results of the misaligned journal bearing are compared with those of the aligned journal bearing. The results show that the distributions of the wear depth, film pressure and elastic deformation are asymmetric along the axial direction and the peak values of them shift toward the back end when the journal misalignment is considered. The maximum wear depth, maximum fluid pressure, maximum contact pressure and maximum elastic deformation of the misaligned journal condition are significantly larger than those of the aligned journal condition.

Geometry and Speed Effects on the Performance of the Herringbone Grooved Gas Lubricated Journal Bearing

2005 ◽  
Author(s):  
D. J. Foster
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Groove Depth ◽  
Bearing Surface ◽  
Static Stiffness ◽  
Groove Pattern ◽  
Land Width

The plain gas lubricated journal bearing is dynamically unstable. The addition of grooving on the bearing surface has been found to overcome this instability. In particular, the herringbone groove pattern has been found to provide damping with increase of static stiffness. The effect of the available geometry characteristics on performance is computed from solution of the compressible Reynolds equation. The geometry features examined are groove angle, and the ratios:- groove depth to clearance, groove-to-land width, axial groove length to bearing length and bearing eccentricity. The performance is determined over a range of compressibility numbers.

Stability Analysis of a Rough Journal Bearing Considering Cavitation Effects

2005 ◽  
Vol 127 (1) ◽  
pp. 112-119 ◽  
Author(s):  
T. V. V. L. N. Rao ◽  
Jerzy T. Sawicki
Keyword(s):  
Stability Analysis ◽  
Governing Equation ◽  
Journal Bearing ◽  
Numerical Procedure ◽  
Instability Threshold ◽  
Bearing Surface ◽  
Surface Configuration

A modified governing equation is derived incorporating the effects of roughness and cavitation in a journal bearing. The available theories of Reynolds roughness and cavitation algorithm proposed by Elrod are utilized in this work to develop a numerical procedure for stability analysis of a liquid lubricated rough journal bearing. The Elrod generalized theory of Reynolds roughness provides a governing equation based on the surface configuration. The Elrod cavitation algorithm conserves mass throughout the bearing and automatically predicts the full film and cavitation regions using a switch function. The roughness is considered on either or both the bearing and journal surfaces. The instability threshold speed increases significantly for the roughness patterns on the grooved bearing surface only at higher eccentricity ratios. The threshold speed increases significantly with increase in the inclination of herringbone type striated roughness patterns on the journal surface from 110° to 150°.

Deterministic Micro Asperities on Bearings and Seals Using a Modified LIGA Process

2004 ◽  
Vol 126 (1) ◽  
pp. 147-154 ◽  
Author(s):  
L. S. Stephens ◽  
R. Siripuram ◽  
M. Hayden ◽  
B. McCartt
Keyword(s):  
Friction Coefficient ◽  
Thrust Bearing ◽  
Average Diameter ◽  
Arbitrary Cross Section ◽  
Surface Metrology ◽  
Bearing Surface ◽  
Viable Option ◽  
Manufacturing Method ◽  
Surface Areas ◽  
Manufacturing Methods

Deterministic micro asperities show potential for enhancement of lubrication in conformal contacts as found in many bearing and seal designs. Several manufacturing methods have been proposed for deterministic micro asperities. Of these, laser texturing has emerged as the most viable option. This paper proposes the LIGA MEMs manufacturing method as an alternative. Using LIGA, surfaces with patterned micron sized surface features of arbitrary cross section (cylindrical, hex, triangular, etc.) can be fabricated from electroplated nickel, gel-cast silicon nitride, or plastic. The resulting asperities can be positive (protuberances) or negative (recesses) and can have heights (depths) from 1–1000 microns and be patterned over surface areas up to about 150mm×150mm. In this paper, the LIGA method is used to fabricate a sample thrust bearing surface with a hexagonal array of positive asperities. The resulting asperities are 550 μm in average diameter, 165 μm in edge-to-edge spacing and have heights of 3–100 μm. Surface metrology indicates submicron accuracy of form and 13 nm Ra roughness on the asperity tops (land). Tribology testing in a nonpressurized oil bath indicates full film conditions and shows a 14–22% reduction in friction coefficient for a thrust surface covered with the micro asperities. A model confirms the experimental trends and indicates the potential to further reduce the friction coefficient by about 60% through optimization of the asperity geometry and layout.

scholarly journals DISTRIBUTION OF THE NORMAL REACTIONS ON THE QUANTOMOBILE WHEELS

2021 ◽  
Vol 6 (4) ◽  
pp. 72-79
Author(s):  
Jurij Kotikov ◽  
Keyword(s):  
Mathematical Model ◽  
Vacuum Energy ◽  
Thrust Bearing ◽  
Vehicle Body ◽  
Physical Vacuum ◽  
Propulsive Force ◽  
Bearing Surface ◽  
Longitudinal Stability ◽  
Analysis And Synthesis ◽  
Programming Analysis

Introduction: The progress of science has made it possible to create new quantum engines (QEs) powered by physical vacuum energy. A QE will generate a vector-based propulsive force, or thrust, applicable to the vehicle body directly, with no transmission required. Traditional cars will be upgraded with QEs and thus converted into quantomobiles. QE thrust application at the point of the vehicle body, hovering above the bearing surface, introduces changes in the traditional diagram of forces acting on the vehicle. Therefore, it is necessary to assess the influence of thrust on the longitudinal stability of the quantomobile. Methods: In the course of the study, we upgraded the diagram of forces acting on the traditional vehicle, by introducing QE thrust (bearing in mind vehicle hovering above the bearing surface). We also developed a corresponding mathematical model for the distribution of the normal reactions on the wheels, taking into account QE placement. Results: Among the developed calculation complexes to perform a qualitative analysis of the influence of force factors on the quantomobile chassis load, a complex representing the longitudinal thrust and the thrust height was distinguished. Discussion: These complexes may serve as the basis of calculation units for more detailed programming, analysis, and synthesis of the design of vehicles with QEs, assessment of the longitudinal stability of the vehicle, optimization of QE placement in the quantomobile body. Example: The method developed is presented using a quantomobile similar to a KamAZ-4326 automobile. Conclusion: The considered diagram of forces acting on a quantomobile, including QE thrust above the bearing surface, shall become generic for force diagrams of quantomobiles with additional thrusters intended to increase the longitudinal stability of the vehicle.

Numerical Investigation on the Mixed Lubrication Performance of Water-Lubricated Coupled Journal and Thrust Bearings

2019 ◽  
Author(s):  
Yanfeng Han ◽  
Guo Xiang ◽  
Jiaxu Wang
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Thrust Bearing ◽  
Journal Bearing ◽  
Load Capacity ◽  
Hydrodynamic Pressure ◽  
Mixed Lubrication ◽  
Eccentricity Ratio ◽  
Thrust Bearings ◽  
Lubrication Performance

Abstract The mixed lubrication performance of water-lubricated coupled journal and thrust bearing (simplified as coupled bearing) is investigated by a developed numerical model. To ensure the continuity of hydrodynamic pressure and flow at the common boundary between the journal and thrust bearing, the conformal transformation is introduced to unify the solution domain of the Reynolds equation. In the presented study, the coupled effects between the journal and thrust bearing are discussed. The effects of the thrust bearing geometric film thickness on the mixed lubrication performance, including the load capacity, contact load and friction coefficient, of the journal bearing are investigated. And the effects of the journal bearing eccentricity ratio on the mixed lubrication performance of the thrust bearing are also investigated. The simulated results indicate the mutual effects between the journal and thrust bearing cannot be ignored in the coupled bearing system. The increasing thrust bearing geometric film thickness generates a decrease in load capacity of journal bearing. There exists an optimal eccentricity ratio of journal bearing that yields the minimum friction coefficient of the thrust bearing.

Buckling of Shear-Deformable Multi-Layered Rings due to Fluid-Pressure Loading

2001 ◽  
Author(s):  
Jack McNamara ◽  
Li Liu ◽  
Anthony M. Waas
Keyword(s):  
Fluid Pressure ◽  
Stacking Sequence ◽  
Finite Element Method Analysis ◽  
Pressure Loading ◽  
Equilibrium Equations ◽  
Nonlinear Equilibrium ◽  
Method Analysis ◽  
Shear Deformable ◽  
Theoretical Results ◽  
Thickness Shear

Abstract This paper is concerned with the analysis of composite rings subjected to external fluid pressure loading. Nonlinear equilibrium equations, linear stability equations, and critical fluid-pressure loads are found for thin multi-layered shear deformable rings. The extensions presented here can be shown to be generalizations of the theory given in [1]. The theory shows that introduction of multiple layers of material introduces coupling between bending and extension. The results are used to show that shear deformation is important when R h < 10 , as well as when the ratio of through thickness shear modulus to Young’s modulus becomes small. The latter has consequences when composite materials are used for the ring layers. The results are also used to show that for coupling between bending and extension the critical fluid-pressure will increase or decrease depending on the stacking sequence. For the example presented in this paper, the predicted critical fluid-pressure loading was higher for the stiffer material located on the inside of a two-layer ring. In all cases, the theoretical results are compared to a finite element method analysis.

Performance Analysis of Grooved Hydrodynamic Journal Bearing with Multi-Depth Textured Surface

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
K.M Faez ◽  
S Hamdavi ◽  
T.V.V.L.N. Rao ◽  
H.H Ya ◽  
Norani M. Mohamed
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Textured Surface ◽  
Plain Bearing ◽  
Bearing Surface ◽  
Grooved Surface ◽  
Hydrodynamic Journal Bearing ◽  
Efficiency And Reliability ◽  
Capacity Performance

In recent research, theoretical studies and investigations for the textured surface of a hydrodynamic journal bearing has been widely used. This is due to the journal bearing’s performance in terms of load capacity which affects the system performance, efficiency and reliability. It has been proven that a textured surface and grooved surface have managed to improve the performance of journal bearings to some extent. In this work, the performance of a grooved hydrodynamic journal bearing has been analysed with a multi-depth textured surface. The study has been conducted using the modified Reynolds equation to numerically solve the load capacity and pressure distribution, respectively. From the results obtained, it was found that the surface complexity features on the journal bearing lowered the load capacity performance when compared to the plain bearing. The pressure, meanwhile, was distributed throughout the textured sections on the bearing surface, even though it was lower as compared to the plain bearing.

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