Investigation of the Failure of Heavily Loaded Journal Bearings

1994 ◽  
Vol 208 (3) ◽  
pp. 167-171
Author(s):  
D Ashman
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Failure Criteria ◽  
Operating Conditions ◽  
Minimum Film Thickness ◽  
Hydrodynamic Solution ◽  
Metrological Study ◽  
Theoretical Minimum

This paper gives details of a combined theoretical and experimental investigation of a plain journal bearing under heavily loaded conditions together with a metrological study of the bearing geometry. It was found that under high loading conditions a simplified analytical expression relating the Sommerfeld number to the non-dimensional minimum film thickness, using a hydrodynamic solution of the isoviscous form of the Reynolds equation, could be developed. An alternative theoretical solution based on elastohydrodynamic lubrication was also considered. In addition, experimental work determined a variety of operating conditions that produced metal-to-metal contact. These operating conditions were then compared with the theoretical minimum film thickness calculations and bearing manufacturing data. This process was used to determine combined failure criteria based on operating conditions and machining capability.

An Experimental Analysis of Misalignment Effects on Hydrodynamic Plain Journal Bearing Performances

2001 ◽  
Vol 124 (2) ◽  
pp. 313-319 ◽  
Author(s):  
J. Bouyer ◽  
M. Fillon
Keyword(s):  
Film Thickness ◽  
Journal Bearing ◽  
Hydrodynamic Pressure ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Maximum Pressure ◽  
Minimum Film Thickness ◽  
Oil Flow ◽  
Hydrodynamic Effects

The present study deals with the experimental determination of the performance of a 100 mm diameter plain journal bearing submitted to a misalignment torque. Hydrodynamic pressure and temperature fields in the mid-plane of the bearing, temperatures in two axial directions, oil flow rate, and minimum film thickness, were all measured for various operating conditions and misalignment torques. Tests were carried out for rotational speeds ranging from 1500 to 4000 rpm with a maximum static load of 9000 N and a misalignment torque varying from 0 to 70 N.m. The bearing performances were greatly affected by the misalignment. The maximum pressure in the mid-plane decreased by 20 percent for the largest misalignment torque while the minimum film thickness was reduced by 80 percent. The misalignment caused more significant changes in bearing performance when the rotational speed or load was low. The hydrodynamic effects were then relatively small and the bearing offered less resistance to the misalignment.

Roughness Amplitude Reduction Under Non-Newtonian EHL Conditions

2005 ◽  
Author(s):  
A. D. Chapkov ◽  
C. H. Venner ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Pressure Fluctuations ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Quantitative Prediction ◽  
Point Contacts ◽  
Minimum Film Thickness ◽  
Roughness Amplitude ◽  
Average Film Thickness ◽  
Ehl Contact

The influence of surface roughness on the performance of bearings and gears operating under ElastoHydrodynamic Lubrication (EHL) conditions has become increasingly important over the last decade, as the average film thickness decreased due to various influences. Surface features can reduce the minimum film thickness and thus increase the wear. They can also increase the temperature and the pressure fluctuations, which directly affects the component life. In order to describe the roughness geometry inside an EHL contact, the amplitude reduction of harmonic waviness has been studied over the last ten years. This theory currently allows a quantitative prediction of the waviness amplitude and includes the influence of wavelength and contact operating conditions. However, the model assumes a Newtonian behaviour of the lubricant. The current paper makes a first contribution to the extension of the roughness amplitude reduction for EHL point contacts including non-Newtonian effects.

Debris Effects on EHL Contact

2000 ◽  
Vol 122 (4) ◽  
pp. 711-720 ◽  
Author(s):  
Young S. Kang ◽  
Farshid Sadeghi ◽  
Xiaolan Ai
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Elastohydrodynamic Lubrication ◽  
Force Balance ◽  
Time Dependent ◽  
Elasticity Equations ◽  
Minimum Film Thickness ◽  
Bounding Surfaces ◽  
Force Balance Equation ◽  
Ehl Contact

A model was developed to study the effects of a rigid debris on elastohydrodynamic lubrication of rolling/sliding contacts. In order to achieve the objectives the time dependent Reynolds equation was modified to include the effects of an ellipsoidal shaped debris. The modified time dependent Reynolds and elasticity equations were simultaneously solved to determine the pressure and film thickness in EHL contacts. The debris force balance equation was solved to determine the debris velocity. The model was then used to obtain results for a variety of loads, speeds, and debris sizes. The results indicate that the debris has a significant effect on the pressure distribution and causes a dent on the rolling/sliding bounding surfaces. Depending on the size and location of the debris the pressure generated within the contact can be high enough to plastically deform the bounding surfaces. Debris smaller than the minimum film thickness do not enter the contact and only large and more spherical debris move toward the contact. [S0742-4787(11)00501-7]

The Elastohydrodynamic Lubrication of Elliptical Point Contacts Operating in the Isoviscous Region

1995 ◽  
Vol 209 (4) ◽  
pp. 225-234 ◽  
Author(s):  
C J Hooke
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Radius Ratio ◽  
Point Contacts ◽  
Reasonable Estimate ◽  
Wide Range ◽  
Minimum Film Thickness

The elastohydrodynamic lubrication of point contacts is examined and results for the minimum film thickness are presented for a wide range of radius ratios and operating conditions. The results are compared with the predictions of the appropriate regime formulae. Although these formulae give a reasonable estimate of the contact's behaviour, the actual clearances are often substantially different, particularly close to the regime boundaries. Interpolation equations for seven values of radius ratio are given and these should be sufficient to allow the minimum clearance to be estimated for most isoviscous point contacts.

Film Thickness and Asperity Load Formulas for Line-Contact Elastohydrodynamic Lubrication With Provision for Surface Roughness

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
M. Masjedi ◽  
M. M. Khonsari
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Reynolds Equation ◽  
Surface Deformation ◽  
Elastohydrodynamic Lubrication ◽  
Load Ratio ◽  
Material Surface ◽  
Line Contact ◽  
Wide Range ◽  
Minimum Film Thickness

Three formulas are derived for predicting the central and the minimum film thickness as well as the asperity load ratio in line-contact EHL with provision for surface roughness. These expressions are based on the simultaneous solution to the modified Reynolds equation and surface deformation with consideration of elastic, plastic and elasto-plastic deformation of the surface asperities. The formulas cover a wide range of input and they are of the form f(W, U, G, σ¯, V), where the parameters represented are dimensionless load, speed, material, surface roughness and hardness, respectively.

Micro Thermal Elastohydrodynamic Lubrication Analysis of Power Law Water-Based Ferrofluid Journal Bearing

2013 ◽  
Vol 694-697 ◽  
pp. 543-546 ◽  
Author(s):  
Xiu Jiang Shi ◽  
You Qiang Wang
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Peak Height ◽  
Bearing Surface ◽  
Roughness Model ◽  
Water Based ◽  
Fluctuation Range ◽  
The Magnetic Field

Based on the Reynolds equation considering the temperature, the effection of non-newtonian and the magnetic field, the elastohydrodynamic lubrication(EHL) analysis of water-based ferrofluid journal bearing were carried out. The influence of roughness peak height and wavelength on the journal bearing surface with cosine roughness model were analysed. The results reveal that the pressure and film thickness of water-based ferrofluid wave apparently with roughness fluctuation; The fluctuation range of pressure and film thickness increase with the increase of roughness peak height, the minimal film thickness decreases; The pressure and film thickness fluctuation range become more and more sparse with the increase of roughness wavelength, the minimal film thickness increases.

Improvement of the THD Performance of a Misaligned Plain Journal Bearing

2003 ◽  
Vol 125 (2) ◽  
pp. 334-342 ◽  
Author(s):  
J. Bouyer ◽  
M. Fillon
Keyword(s):  
Film Thickness ◽  
Flow Rate ◽  
Journal Bearing ◽  
Numerical Study ◽  
Axial Flow ◽  
Hydrodynamic Pressure ◽  
Operating Conditions ◽  
Local Defect ◽  
Minimum Film Thickness ◽  
Global Defect

This numerical study deals with the improvement of the thermohydrodynamic performance of a 100 mm plain journal bearing submitted to a constant misalignment torque under steady-state conditions. The performance of the misaligned journal bearing is improved by adding either a local or a global defect to the bearing geometry. The influence on bearing performance of the local defect, situated in the zone of minimum film thickness, is analyzed by using various widths and lengths of defect. A global defect, which is conical in shape and is located at one end of the bearing, is also studied under varying direction and magnitude of misalignment torque. Our main focus was on hydrodynamic pressure, temperature distributions at the film/bush interface, oil flow rate, power losses and film thickness. The defects significantly improved the performance of the bearing. The minimum film thickness increased by more than 60 percent and the temperature decreased, whilst the axial flow rate was barely affected. Thus, the defects can be an effective solution for misaligned bearings when they are submitted to extreme operating conditions.

Elastohydrodynamic Lubrication of Rough Surfaces Under Oscillatory Line Contact With Non-Newtonian Lubricant

2007 ◽  
Author(s):  
Mongkol Mongkolwongrojn ◽  
Khanittha Wongseedakaew ◽  
Francis E. Kennedy
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Power Law ◽  
Reynolds Equation ◽  
Initial Conditions ◽  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication ◽  
Oscillatory Motion ◽  
Line Contact ◽  
Minimum Film Thickness

This paper presents the analysis of elastohydrodynamic lubrication (EHL) of two parallel cylinders in line contact with non-Newtonian fluids under oscillatory motion. The effects of transverse harmonic surface roughness are also investigated in the numerical simulation. The time-dependent Reynolds equation uses a power law model for viscosity. The simultaneous system of modified Reynolds equation and elasticity equation with initial conditions was solved using multi-grid multi-level method with full approximation technique. Film thickness and pressure profiles were determined for smooth and rough surfaces in the oscillatory EHL conjunctions, and the film thickness predictions were verified experimentally. For an increase in the applied load on the cylinders, the minimum film thickness calculated numerically becomes smaller. The predicted film thickness is slightly higher than the film thickness obtained experimentally, owing to cavitation that occurred in the experiments. For both hard and soft EHL contacts, the minimum film thickness under oscillatory motion is very thin near the trailing edge of the contact, especially for stiffer surfaces. The surface roughness and power law index of the non-Newtonian lubricant both have significant effects on the film thickness and pressure profile between the cylinders under oscillatory motion.

The Minimum Film Thickness in Lubricated Line Contacts during a Reversal of Entrainment—Piezoviscous Behaviour

1992 ◽  
Vol 206 (6) ◽  
pp. 417-424 ◽  
Author(s):  
C J Hooke
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Lubrication Theory ◽  
Rate Of Change ◽  
Operating Conditions ◽  
Entrainment Velocity ◽  
Residual Film ◽  
Minimum Film Thickness ◽  
Line Contacts ◽  
Important Exception

In many line contacts the operating conditions, such as load, entrainment velocity and contact radii, vary with time. Generally, the results from standard elastohydrodynamic lubrication theory, derived for constant conditions, can be used to obtain a quasi-steady prediction of film thickness that is sufficiently accurate for design purposes. An important exception to this is where the entrainment direction changes because, under those conditions, the quasi-steady approach predicts that there will be no clearance between the surfaces while in practice a residual film will persist. A previous paper showed that the minimum film thickness during entrainment reversal depends primarily on the rate of change of entrainment velocity. Limit expressions for the minimum clearance in the four regimes of lubrication were obtained. The present paper is part of a programme to develop a minimum film thickness chart for entrainment reversal and deals with the transition between the rigid-piezoviscous and the elastic-piezoviscous regimes.

Elastohydrodynamic Lubrication of Soft, Highly Deformed Contacts

1972 ◽  
Vol 14 (1) ◽  
pp. 34-48 ◽  
Author(s):  
C. J. Hooke ◽  
J. P. O'Donoghue
Keyword(s):  
Film Thickness ◽  
Contact Pressure ◽  
Journal Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Theoretical Solution ◽  
Minimum Film Thickness ◽  
Ring Seal ◽  
The Relationship ◽  
Maximum Contact

Part 1 presents a theoretical solution to the problem of lubrication of soft, highly deformed surfaces. It is argued that with this type of contact the inlet and outlet regions can be separated and analysed independently. This approach leads to a single value of non-dimensional film thickness at the point of maximum contact pressure and to a non-dimensional minimum film thickness dependent on the relationship between the inlet and outlet parameters. In Part 2, these results are applied to the problems of a cylinder sliding on an elastomer lined surface, an elastomer lined journal bearing and a sliding O-ring seal.

Sign in / Sign up

Export Citation Format

Share Document