Experimental Investigation on PTFE Composites for Journal Bearings

2007 ◽  
Author(s):  
V. Jayaraj ◽  
K. Srinivasan
Keyword(s):  
Thin Film ◽  
Hydrodynamic Lubrication ◽  
Industrial Applications ◽  
Journal Bearings ◽  
Lubricating Oil ◽  
Lubricating Film ◽  
Ideal Situation ◽  
Rolling Element ◽  
Heavy Loads ◽  
Ptfe Composites

Journal bearings are widely used in many industrial applications. In journal bearings, under boundary lubricated conditions, the surfaces are considered to be technically dry or only slightly lubricated, so that the resistance to relative motion is due to the interaction between the highest asperities covered by the boundary film. A thin film of lubricating oil exists under this condition and there is partial metal to metal contact. The ideal situation where the two sliding surfaces are completely separated by a thin film of a viscous fluid or a gas is referred to as hydrodynamic lubrication. In hydrodynamic bearings, due to frequent starting and stopping, misalignment of the shaft with the bearing, application of heavy loads and unexpected sudden non flow of lubricant and such other service conditions result in boundary lubrication by squeezing out the lubricating film or allow the surface asperities to break through the film so that the shaft and bearing are pressed into contact with one another. The maximum wear occurs in fluid film bearings during boundary lubricated conditions. The use of dry bearings has therefore become more essential as it requires practically no lubricant to function. Moreover it is less expensive, resist contamination better compared to rolling element bearings and easier to design.

Bearing Design and Lubrication

2021 ◽  
pp. 141-161
Author(s):  
Karl Kollmann ◽  
Calum E. Douglas ◽  
S. Can Gülen
Keyword(s):  
High Sensitivity ◽  
Journal Bearings ◽  
Lubricating Oil ◽  
Rolling Element Bearings ◽  
Complete Evaluation ◽  
Overall Design ◽  
Rolling Element ◽  
Oil Flow ◽  
Bearing Design ◽  
Outside Diameter

High rotational speeds of the impeller call for careful bearing design and layout, not just those on the supercharger impeller shaft itself but also on any preceding shafts, which may run at lower speed. The question of whether to use plain (journal) bearings or rolling element bearings can only be decided after a complete evaluation of the overall design of the supercharger drive system in question. Journal bearings are in general smaller in outside diameter and despite the higher overall length have a lower weight than rolling element bearings. Journal bearings demand several times the lubricating oil flow rate than rolling element bearings, and they also exhibit high sensitivity to particulates in the oil and the overall quality thereof.

Comparative Evaluation of MoS2 and WS2 as Powder Lubricants in High Speed, Multi-Pad Journal Bearings

1999 ◽  
Vol 121 (3) ◽  
pp. 625-630 ◽  
Author(s):  
C. Fred Higgs ◽  
Crystal A. Heshmat ◽  
Hooshang Heshmat
Keyword(s):  
Comparative Evaluation ◽  
High Speed ◽  
Solid Lubricants ◽  
Extreme Environment ◽  
Journal Bearings ◽  
Lubricating Film ◽  
Constant Friction ◽  
Traction Coefficient ◽  
Limiting Value ◽  
Selection Of

As part of a program to develop solid/powder-lubricated journal bearings, a comparative evaluation has been performed to aid in determining whether MoS2 and WS2 powder are suitable lubricants for high-speed, extreme-environment multi-pad journal bearings. Plots of traction coefficients, friction, frictional power loss, and bearing pad temperature are presented as a means for comparing various powder lubricants. This paper primarily focuses on experiments carried out on a three-pad journal bearing and a disk-on-disk tribometer. Results showed that MoS2 traction curves resemble that of SAE 10 synthetic oil. Unlike liquid lubricants, powder films have a limiting shear strength property. Once the powder reaches this limiting value, the maximum traction coefficient is limited and the powder essentially shears along sliding walls. Experimental traction data shows evidence of this property in various powders. The thermal performance of the bearing was evaluated at speeds up to 30,000 rpm and loads up to 236 N. Although WS2 displayed constant friction coefficient and low temperature with increasing dimensionless load, MoS2 exhibited frictional behavior resembling that of a hydrodynamic lubricating film. In this paper, an attempt has been made to provide a criterion for the selection of solid lubricants for use in those tribosystems that may be operated in a high speed/load regime (i.e., high strain rates) as an alternative yard stick to conventional comparative approaches.

Simultaneous Monitoring of Rolling-Element and Journal Bearings Using Analysis of Structure-Born Ultrasound Acoustic Emissions

2010 ◽  
Author(s):  
A. Albers ◽  
M. Dickerhof
Keyword(s):  
Acoustic Emission ◽  
Acoustic Emissions ◽  
Piezoelectric Sensor ◽  
Journal Bearings ◽  
Rolling Element Bearings ◽  
Acoustic Emission Sensor ◽  
Outer Race ◽  
Rolling Element ◽  
Characteristic Values ◽  
Acoustic Emission Technology

The application of Acoustic Emission technology for monitoring rolling element or hydrodynamic plain bearings has been addressed by several authors in former times. Most of these investigations took place under idealized conditions, to allow the concentration on one single source of emission, typically recorded by means of a piezoelectric sensor. This can be achieved by either eliminating other sources in advance or taking measures to shield them out (e. g. by placing the acoustic emission sensor very close to the source of interest), so that in consequence only one source of structure-born sound is present in the signal. With a practical orientation this is often not possible. In point of fact, a multitude of potential sources of emission can be worth considering, unfortunately superimposing one another. The investigations reported in this paper are therefore focused on the simultaneous monitoring of both bearing types mentioned above. Only one piezoelectric acoustic emission sensor is utilized, which is placed rather far away from the monitored bearings. By derivation of characteristic values from the sensor signal, different simulated defects can be detected reliably: seeded defects in the inner and outer race of rolling element bearings as well as the occurrence of mixed friction in the sliding surface bearing due to interrupted lubricant inflow.

Modeling and experimental research on engaging characteristics of wet clutch

2019 ◽  
Vol 71 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Yanzhong Wang ◽  
Yuan Li ◽  
Yang Liu ◽  
Wei Zhang
Keyword(s):  
Contact Surface ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Lubricating Oil ◽  
Centrifugal Effect ◽  
Element Analysis ◽  
Content Type ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Engagement Process

PurposeTo gain in-depth understandings of engaging characteristics, the purpose of this paper is to improve the model of wet clutches to predict the transmitted torque during the engagement process.Design/methodology/approachThe model of wet clutch during the engagement process took main factors into account, such as the centrifugal effect of lubricant, permeability of friction material, slippage factor of lubricant on contact surface and roughness of contact surface. Reynolds’ equation was derived to describe the hydrodynamic lubrication characteristics of lubricant film between the friction plate and the separated plate, and an elastic-plastic model of the rough surfaces contact based on the finite element analysis was used to indicate the loading force and friction torque of the contact surface.FindingsThe dynamic characteristics of wet clutch engagement time, relative speed, hydrodynamic lubrication of lubricating oil, rough surface contact load capacity and transfer torque can be obtained by the wet clutch engagement model. And the influence of the groove shape and depth on the engaging characteristics is also analyzed.Originality/valueThe mathematical model of the wet clutch during the engagement process can be used to predict the engaging characteristics of the wet clutch which could be useful to the design of the wet clutch.

Surfaces with pores: hydrodynamic lubrication

2017 ◽  
Vol 69 (4) ◽  
pp. 471-483 ◽  
Author(s):  
Leonid Burstein
Keyword(s):  
Design Methodology ◽  
Hydrodynamic Lubrication ◽  
Dimensional Model ◽  
Hydrodynamic Behavior ◽  
Content Type ◽  
One Dimensional ◽  
Lubricating Film ◽  
Cell Dimensions ◽  
Practical Implications ◽  
Pore Cell

Purpose This paper aims to assess the hydrodynamic lubrication of two opposing surfaces with identical pores having a semicircular profile. The surfaces are treated with more than one pore that allows clarification of whether there exists interaction between the pores. Design/methodology/approach A transient, spatial, one-dimensional model of surfaces with regular pores was developed and applied in the context of fluid lubrication. MATLAB software has been used. Findings Calculations show that a lubricating film between two surfaces with pores provides better hydrodynamic conditions in comparison to that on one surface with pores. It was also shown that the pores of one surface act as separate objects and can take into account only the interaction between the pores of the opposite surfaces. In addition, it was found that there are optimum values of the pore radii, gap and pore cell dimensions at which the bearing capacity of the film is maximal. Practical implications The computer program used for the pore parameter calculations provided the optimal lubrication. Originality/value This is the first study of the lubricating film hydrodynamic behavior of two opposite surfaces with pores having a semicircular profile.

Influence of Hydrodynamic Journal Bearings With Multiple Slip Zones on Rotordynamic Behavior

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
A. Bhattacharya ◽  
J. K. Dutt ◽  
R. K. Pandey
Keyword(s):  
Slip Length ◽  
Stability Limit ◽  
Substantial Improvement ◽  
Journal Bearings ◽  
Heat Diffusion ◽  
Small Range ◽  
Heat Diffusion Equation ◽  
Multiple Slip ◽  
Lubricating Film ◽  
Marginal Improvement

This paper mainly reports stability investigations of rotors supported on fluid film journal bearings possessing multilocational slip-no-slip zones at the bush–film interface. The coupled solution of governing equations (Reynolds equation, energy equation, heat diffusion equation, lubricant rheological relation, and thermal boundary conditions) has been used to find pressure distributions in the lubricating film followed by evaluation of bearing coefficients. These coefficients have been used to determine stability limit speed (SLS) of the system and its robustness for both short (nearly inflexible) and long (flexible) rotors. Numerical simulations show that the pattern of pressure distribution with multiple slip-no-slip zones is similar to that obtained for multilobe bearings, resulting in substantial improvement of rotor–bearing stability irrespective of eccentricity ratio. A reduction in friction force (up to Sommerfeld number 1.8) and an increase in SLS and robustness compared to conventional bearings are observed when used with short rotors. Typically, up to six pairs of slip-no-slip zones improve SLS of the rotor–shaft system and robustness for short rotors, although more pairs deteriorate both. However, for long rotors, where dynamic rotor forces also act, these bearings provide marginal improvement in stability and robustness only for a small range of slip length.

Performance of Stern Tube Bearings under Different Lubrication and Operating Conditions

2009 ◽  
Author(s):  
Jan H. Andersen ◽  
Hiroyuki Sada ◽  
Seiji Yamajo
Keyword(s):  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Water Soluble ◽  
Analysis Tool ◽  
Test Rig ◽  
Experimental Performance ◽  
Shaft Alignment ◽  
Alignment Analysis

This paper presents the results of an investigation into the theoretical and experimental performance of oil lubricated journal bearings. DNV has developed a new calculation tool for the analysis of journal bearing performance as part of shaft alignment analysis. The results of the calculation tool have been compared to other research and analysis methods under static and dynamic conditions. In addition, white metal bearings were tested with decreasing Sommerfeld number until loss of hydrodynamic lubrication. The experiments were carried out in a bearing test rig and with three different lubricants, normal mineral oil, emulsifying oil, and water-soluble oil. The tests were done with increasing water content in the lubricant. Results from the test were compared with calculation using the DNV analysis tool.

Effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions

2020 ◽  
Vol 21 (3) ◽  
pp. 301
Author(s):  
Chongpei Liu ◽  
Wanyou Li ◽  
Xiqun Lu ◽  
Bin Zhao
Keyword(s):  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Lubricating Oil ◽  
Asperity Contact ◽  
Adiabatic Flow ◽  
Lubrication Performance ◽  
Load Carrying ◽  
Edge Wear ◽  
Journal Misalignment

The textures on the bushing surface have important effects on the performance of journal bearing. In this study, the effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions are investigated theoretically. The journal misalignment, asperity contact and thermal effects are considered, while the profile modifications due to running-in are neglected. The Winkler/Column model is used to calculate the elastic deformation of bushing surface and the adiabatic flow hypothesis is adopted to obtain the effective temperature of lubricating oil. The numerical solution is established by using finite difference and overrelaxation iterative methods, and the rupture zone of oil film is determined by Reynolds boundary conditions. The numerical results reveal that the double parabolic profiles with groove textures with proper location and geometric sizes can increase load carrying capacity and reduce friction loss under steady operating conditions, which effectively overcome the drawbacks of double parabolic profiles. This novel bushing profile may help to reduce the bushing edge wear and enhance the lubrication performance of journal bearing.

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