Hydrodynamic Aspects of Fatigue in Plain Journal Bearings

1981 ◽  
Vol 103 (1) ◽  
pp. 150-156 ◽  
Author(s):  
F. A. Martin ◽  
D. R. Garner ◽  
D. R. Adams
Keyword(s):  
Hydrodynamic Pressure ◽  
Journal Bearings ◽  
Pressure Variation ◽  
Hydrodynamic Characteristics ◽  
Specific Load ◽  
Bearing Material ◽  
Significant Term ◽  
Bearing Materials ◽  
Negative Pressures ◽  
The University

The fatigue resistance of different bearing materials is usually given an “order of merit” in terms of specific load on the bearing. The bearing material cannot directly sense the applied specific load, since it is the hydrodynamic oil film pressures which directly create the stresses in the lining; both pressures and stresses need to be examined to see if a more meaningful criterion for fatigue can be found. As a first step in this study the experimental fatigue work carried out by Gyde at the University of Denmark was examined and compared with trends in peak specific load, hydrodynamic characteristics, and bearing lining stresses. It has been shown that peak specific load and peak hydrodynamic pressure are not in themselves realistic parameters, but that pressure variation on a bearing element, perhaps including some rapidly forming negative pressures, could be a significant term. The study of the more fundamental material stresses has not yet been extended to allow for the influence of any nonpositive film pressures, but results so far follow similar trends to those obtained on the pressure variation criterion.

Running-in effects on friction of journal bearings under slow sliding speeds

2019 ◽  
Vol 234 (3) ◽  
pp. 362-372
Author(s):  
A Linjamaa ◽  
A Lehtovaara ◽  
M Kallio ◽  
A Léger
Keyword(s):  
Journal Bearings ◽  
Mixed Lubrication ◽  
Bearing Material ◽  
Environmentally Sustainable ◽  
Tin Bronze ◽  
Bearing Materials ◽  
Stribeck Curves ◽  
Remarkable Reduction ◽  
Lubrication Conditions ◽  
Film Lubrication

Hydrodynamic thrust and journal bearings are facing challenges in modern heavy-duty machinery where full film lubrication cannot always be achieved or sustained. This is due to reasons such as start–stop operation, increased power density and the use of thinner lubricants. Although this leads to increased overall efficiency, bearings are operating more often under mixed lubrication conditions. This is why the running-in behavior of the bearing material is important. In this study, running-in behavior of traditional leaded tin bronze and its environmentally sustainable alternative, bimetal bismuth, was studied. Experimental friction tests were performed with journal bearings under full film and mixed lubrication conditions in order to find the Stribeck curves. The results are analyzed using frictional energy, and friction coefficient values based on continuous friction monitoring. Remarkable reduction of friction was observed with both bearing materials due to running-in.

A Study of Transient Response of Flexible Rotors in High Speed Turbomachinery

1992 ◽  
Author(s):  
V. Pavelic ◽  
R. S. Amano
Keyword(s):  
Mathematical Model ◽  
Computer Program ◽  
Analytical Model ◽  
High Speed ◽  
Angular Speed ◽  
Journal Bearings ◽  
Hydrodynamic Characteristics ◽  
Flexible Assembly ◽  
Lagrange’S Equation ◽  
Equations Of Motions

In many applications the design operating range of the turbomachinery may be well above the rotor first critical speed which leads to the problem of insuring that the turbomachinery performs with a stable, low-level amplitude of vibration. Under certain conditions of high speed and loading the rotor system can start orbiting in its bearing at a rate which is less than the rotor angular speed, and this phenomena is commonly known as whirling or whipping action. This whipping action may produce additional undesirable dynamic loads on the overall flexible assembly and eventually destroy the rotor. Some of this action is also transient in nature. Whirling is a self-exited vibration caused mainly by the fluid bearings and by the internal friction damping of the rotor. To understand this occurrence, a general dynamic mathematical model was derived considering also the complete viscous characteristic of hydrodynamic journal bearings. The general equations of motions of the system are obtained from Lagrange’s equation of motion. The system kinetic, potential, and dissipation functions are determined based on the generalized coordinates of the system. The journal displacements are related to the overall dynamics of the rotor using deformable bearings. The loads acting at the journals of the shaft are integrated from the fluid film pressure distribution in the journal bearings using mobility method. A unique mathematical model is formulated and solved. This model includes the elastic and inertial properties of the flexible rotor, the elastic, damping and inertial properties of supports and the hydrodynamic characteristics of the journal bearings. The equations of motions result in a system of nonlinear second order differential equations which are solved by using finite difference method. The solution of the equations of motions is used to plot maps of motion of journal centers. A computer program was implemented to aid in the solution of the system of equations and to verify analytical model. The computer program used test data available in literature and the results were compared to be very good. The analytical model and results obtained in this study can be of great help to designers of high speed turbomachinery.

scholarly journals Observation of Pressure Variation in the Cavitation Region of Submerged Journal Bearings

1982 ◽  
Vol 104 (2) ◽  
pp. 157-163 ◽  
Author(s):  
I. Etsion ◽  
L. P. Ludwig
Keyword(s):  
Journal Bearing ◽  
Reverse Flow ◽  
Ambient Pressure ◽  
Journal Bearings ◽  
Pressure Variation ◽  
Pressure Measurements ◽  
Pressure Profiles ◽  
Cavitation Region ◽  
Cavitation Pressure ◽  
Visual Observations

Visual observations and pressure measurements in the cavitation zone of a submerged journal bearing are described. Tests were performed at various shaft speeds and ambient pressure levels. Some photographs of the cavitation region are presented showing strong reverse flow at the downstream end of the region. Pressure profiles are presented showing significant pressure variations inside the cavitation zone, contrary to common assumptions of constant cavitation pressure.

Tribological Studies on Oscillating Bronze Bearings Lubricated With Environmentally Adapted Lubricants (EALs)

2004 ◽  
Author(s):  
Jan Ukonsaari ◽  
Elisabet Kassfeldt
Keyword(s):  
Surface Layer ◽  
Mineral Oil ◽  
Tribological Performance ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Bearing Surface ◽  
Bearing Material ◽  
Sliding Bearings ◽  
Synthetic Ester ◽  
Tin Bronze

Different compositions of bronze materials are used for sliding bearings in various applications including those involving oscillatory motion and moderate temperatures. The compatibility of new environmentally adapted synthetic esters with different contacting surface materials is important to ensure good tribological performance. The present work deals with tribological studies on oscillatory journal bearings manufactured with three different compositions of bronze materials lubricated with EALs under boundary lubricated conditions. Under certain operating conditions, dissolution of alloying constituents from the bronze bearing material dissolute into the synthetic ester lubricant occur leading to the formation of a copper enriched bearing surface layer. Tin-bronze with synthetic ester lubricant showed more stable friction values and roughly ten times better wear results than the harder aluminium- and manganese-bronze and also outperformed the mineral oil under the same conditions.

Study of Conical Whirl Instability of Self-Acting Porous Gas Journal Bearings Considering Tangential Velocity Slip

1988 ◽  
Vol 110 (1) ◽  
pp. 139-143
Author(s):  
S. K. Guha ◽  
N. S. Rao ◽  
B. C. Majumdar
Keyword(s):  
Tangential Velocity ◽  
Hydrodynamic Pressure ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Stability Characteristic ◽  
Damping Coefficients ◽  
Conical Whirl ◽  
Angular Displacements ◽  
Stiffness And Damping ◽  
Film Interface

The purpose of the present work is to study theoretically the conical whirl instability of unloaded self-acting porous gas journal bearings considering the tangential velocity slip at the bearing-film interface. The hydrodynamic pressure developed in the bearing clearance due to angular displacements of the journal at the midplane of the bearing is obtained by the simultaneous solution of equation of continuity in the porous medium and the modified Reynolds equations, satisfying the appropriate boundary conditions. With the help of the dynamic tilting stiffness and damping coefficients, stability characteristic is obtained. The effects of various parameters on conical stability parameter have been investigated for a nongyroscopic system.

CFD Analysis of Hydrodynamic Pressure Distribution in Non-Newtonian Oil in Journal Bearing Lubrication Gap

2015 ◽  
Vol 220-221 ◽  
pp. 37-42 ◽  
Author(s):  
Adam Czaban
Keyword(s):  
Shear Stress ◽  
Pressure Distribution ◽  
Journal Bearing ◽  
Hydrodynamic Pressure ◽  
Journal Bearings ◽  
Lubricating Oil ◽  
Cfd Analysis ◽  
Relationship Power ◽  
Lift Capacity ◽  
Relative Eccentricity

This paper presents the results of CFD analysis of the hydrodynamic pressure distribution in slide journal bearings lubricated by non-Newtonian oil. It was assumed that the oil shear stress varies from shear rate according to the Ostwald–de Waele relationship (power law lubricant). The comparison was related to bearings differences only in properties of lubricating oil – Newtonian and non-Newtonian properties; other parameters for both in each case were the same. The Tables show relative decrease of the maximum hydrodynamic pressure value and bearing lift capacity according to the bearing lubricated with Newtonian oil, for different values of bearing relative eccentricity.

Effect of bearing materials on journal bearings under TEHL with lubricant based on Carreau model

2019 ◽  
Vol 43 (2) ◽  
pp. 162-170
Author(s):  
Waleephan Gunnuang ◽  
Chatchai Aiumbhornsin ◽  
Jittraporn Wongsa-Ngam ◽  
Mongkol Mongkolwongrojn
Keyword(s):  
Journal Bearings ◽  
Carreau Model ◽  
Bearing Materials

Tribological Relationship for Sintered Bearing Using Taguchi Technique

2015 ◽  
Vol 3 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Priya Shekhar Gajjal ◽  
Geeta Lathkar ◽  
Harijan Bagchi
Keyword(s):  
Regression Analysis ◽  
Process Parameters ◽  
Friction And Wear ◽  
Journal Bearing ◽  
Taguchi Technique ◽  
Bearing Material ◽  
Sintered Bearing ◽  
Bearing Materials ◽  
The Relationship ◽  
Manufacturing Parameters

Sintered bearing materials have been developed in order to be used as a journal bearing material without lubrication. This paper presents a study of influence of manufacturing and process parameters on friction and wear of bearing. Plan of experiments, based on Taguchi technique was used to acquire the data in a controlled way. An orthogonal array (L27) and analysis of variance were employed to investigate the influence of parameters of dry ferrous bearing. The objective is to establish a correlation between process and manufacturing parameters with friction and wear by multiple regression analysis. Finally, confirmation tests were performed to validate the relationship as suggested through experiments.

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