Influence of a Surface Bump or Groove on the Lubricating Performance and Dimple Phenomena in Simple Sliding Point EHL Contacts

2004 ◽  
Vol 126 (3) ◽  
pp. 466-472 ◽  
Author(s):  
Peiran Yang ◽  
Jinlei Cui ◽  
Motohiro Kaneta ◽  
Hiroshi Nishikawa
Keyword(s):  
Numerical Solution ◽  
Significant Influence ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Optical Interferometry ◽  
Steel Ball ◽  
Experimental Results ◽  
Oriented Surface ◽  
Glass Disk ◽  
Good Agreement

The influence of a transversely or longitudinally oriented surface bump or groove on the lubricating performance and dimple phenomena in the simple sliding point contact composed of a steel ball and a glass disk has been investigated theoretically with numerical solution of the thermal elastohydrodynamic lubrication (EHL) and experimentally with optical interferometry technique. Good agreement has been obtained between the theoretical and experimental results. It has also been discovered that the surface bump or groove is dangerously harmful to the lubricating performance and has a significant influence on the dimple phenomena.

Local Reduction in Thickness of Point Contact EHL Films Caused by a Transversely Oriented Moving Groove and Its Recovery

1994 ◽  
Vol 116 (3) ◽  
pp. 635-639 ◽  
Author(s):  
M. Kaneta ◽  
H. Nishikawa
Keyword(s):  
Shear Flow ◽  
Film Thickness ◽  
Relative Size ◽  
Point Contact ◽  
Transient Behavior ◽  
Optical Interferometry ◽  
Steel Ball ◽  
Groove Surface ◽  
Glass Disk ◽  
Local Reduction

Transient behavior of elastohydrodynamic (EHL) films caused by a transversely oriented groove passing through the EHL conjunction is directly observed using the optical interferometry technique. A steel ball on which the groove is formed is run against a smooth glass disk under conditions of rolling with sliding. It is shown that a local reduction in film thickness caused by the groove and its recovery depend strongly on shear flow dominating the EHL conjunction and side leakage along the groove. Surface kinematic conditions and the relative size of the groove with respect to the overall film thickness have also profound effects on the above phenomena.

Theoretical and experimental studies of the oil film in lubricated point contact

1966 ◽  
Vol 291 (1427) ◽  
pp. 520-536 ◽  
Keyword(s):  
Surface Layer ◽  
Film Thickness ◽  
Strong Evidence ◽  
Experimental Studies ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Experimental Results ◽  
Point Contacts ◽  
Previous Theory ◽  
Oil Film

A technique using Newton’s rings for mapping the oil film of lubricated point contacts is described. A theoretical value for the film thickness of such contacts in elastohydrodynamic lubrication is derived. The experimental results give the exit constriction predicted by previous theory but never shown in detail. The comparison of theoretical and experimental oil film thicknesses, which is satisfactorily accurate, gives strong evidence for a viscous surface layer some 1000Å thick. This film agrees with the known ‘lubricating power’ of the various oils tested.

PTFE and MoS2 Additives for Mineral Oil Film Formation in EHL Point Contacts

2016 ◽  
Author(s):  
Glenn Kwabena Gyimah ◽  
Zhongning Guo ◽  
Ping Huang ◽  
Shuzhen Jiang ◽  
Gary C. Barber
Keyword(s):  
Film Thickness ◽  
Viscosity Index ◽  
Point Contact ◽  
Rolling Speed ◽  
Optical Interferometry ◽  
Lubricant Film ◽  
Steel Ball ◽  
Engine Oil ◽  
Lubricant Film Thickness ◽  
Viscosity Index Improvers

Lubricant film-forming viscosity index improvers blended with commercial engine oil have been developed and studied by using optical interferometry. The influence of the viscosity index improvers (PTFE and MoS2) mixed with oil were experimentally studied and compared with engine oil without the index improvers as the baseline. The effect of the viscosity index improvers on lubricant film thickness, contact pressure and rolling speed for the case of a steel ball loaded on a flat glass surface in point contact condition was investigated. An optical interferometry technique which utilized a monochromatic two-beam interferometry light source, a microscope and a high-speed video recording device was used for the investigation. Hamrock and Dawson calculations for EHL film thickness were also used for comparative analysis. The lubricants used were commercial SAE #30 engine oil and PTFE and MoS2 mixed with commercial SAE #30 engine oil. The oil viscosities ranged from 0.0109 Pa.s to 0.255 Pa.s. The rolling speed and the loads were varied between 0.189 m/s to 0.641 m/s and 1 N to 2.6 N respectively. The lubricant film thickness stability at the point of contact between the steel ball and the glass disc was investigated for both steady and rolling state conditions. The viscosity index improvers were found to have a significant effect on the film thickness behavior under pure rolling point contact conditions.

Solution of the Non-Newtonian Elastohydrodynamic Problem for Circular Contacts Based on a Flow Continuity Method

1996 ◽  
Vol 210 (4) ◽  
pp. 247-258 ◽  
Author(s):  
C A Holt ◽  
H P Evans ◽  
R W Snidle
Keyword(s):  
Film Thickness ◽  
Numerical Solution ◽  
Control Volume ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Theoretical Formulation ◽  
New Approach ◽  
Limiting Shear Stress ◽  
Pure Rolling ◽  
Stress Behaviour

The paper describes a numerical solution method for the point contact elastohydrodynamic lubrication (EHL) problem under non-Newtonian, isothermal conditions. The theoretical formulation of the non-Newtonian effect is general and may be applied to both shear thinning and limiting shear stress behaviour. The particular rheological model investigated in this work is the Eyring ‘sinh law’ relation. The numerical solution of the lubrication equations is based upon a control volume approach rather than the more usual methods that utilize a modified Reynolds equation. This new approach ensures that flow continuity is satisfied at the discretization level. Results are presented to show the effect of non-Newtonian behaviour on film thickness and pressure distribution in circular EHL contacts operating over a range of slide-roll ratios from 0 (pure rolling) to 1.5. Under conditions of pure rolling or low sliding there is found to be little effect of non-Newtonian behaviour, but at the highest degree of sliding the film thickness over the central, flattened area of the contact is reduced by up to 10 per cent at the highest rolling speed of 0.75 m/s.

Effects of Asperities in Elastohydrodynamic Lubrication

1980 ◽  
Vol 102 (3) ◽  
pp. 374-378 ◽  
Author(s):  
M. Kaneta ◽  
A. Cameron
Keyword(s):  
Film Thickness ◽  
Glass Plate ◽  
Three Dimensional ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Critical Value ◽  
Optical Interferometry ◽  
Asperity Height ◽  
Height Ratio ◽  
Pure Rolling

Optical interferometry was used to study rough surfaces under lubricated point contact. Three dimensional “asperities” of chromium were sputtered onto a steel ball which was run against a smooth glass plate under both rolling and sliding. The experimental results were compared with the various published theories. The film thicknesses found in sliding are different from those observed in pure rolling, which are nearly equal to the theoretical values. Film thickness collapse occurred when the central film thickness/half asperity height ratio (λ ratio) reached a critical value.

scholarly journals Optimization of EDM Parameters for Production of Biomedical Materials

2021 ◽  
Vol 7 (2) ◽  
pp. 1-8
Author(s):  
Mukesh Kumar Rakesh ◽  
Dr. Syed Faisal Ahmed
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Solution ◽  
Literature Survey ◽  
Experimental Results ◽  
Physical Parameters ◽  
The Finite Element Method ◽  
Critical Areas ◽  
Cylindrical Cup ◽  
Good Agreement

The finite element method (FEM) is used for simulating complex intricate shapes of industrial sheet forming operation. Effective physical parameters, as well as the numerical solution, influence the parameters of this phenomenon and its numerical prediction of results. In this study, to investigate the influence of different embossing patterns and embossing depths on the critical areas appearing during deep-drawn of a cylindrical cup. The numerical results are found from the literature survey to be in good agreement with the experimental results and accurate thinning distributions had been predict.

scholarly journals Transient analysis of isothermal elastohydrodynamic circular point contacts

2001 ◽  
Vol 215 (10) ◽  
pp. 1159-1172 ◽  
Author(s):  
D Jalali Vahid ◽  
H Rahnejat ◽  
Z M Jin ◽  
D Downson
Keyword(s):  
Transient Analysis ◽  
Solution Method ◽  
Numerical Solutions ◽  
Flat Glass ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Point Contacts ◽  
Good Qualitative Agreement ◽  
Circular Point ◽  
Good Agreement

In this paper a solution method is presented for the transient isothermal elastohydrodynamic lubrication of point contact conjunctions, based upon the Newton-Raphson scheme and low iteration relaxation. The numerical results are compared with the numerical and experimental observations of others for the circular point contact of a ball against a flat glass disc under oscillating conditions. Good agreement has been found with other numerical solutions. The comparison with the experimental results shows good qualitative agreement.

Quantitative Comparisons Between Measured and Solved EHL Dimples in Point Contacts

2002 ◽  
Vol 125 (1) ◽  
pp. 210-214 ◽  
Author(s):  
P. Yang ◽  
M. Kaneta and ◽  
S. Masuda
Keyword(s):  
Flow Model ◽  
Optical Interferometry ◽  
Numerical Results ◽  
Experimental Results ◽  
Point Contacts ◽  
Newtonian Flow ◽  
Glass Disk ◽  
Traction Coefficient ◽  
Thermal Ehl ◽  
The Relationship

Using a mineral bright stock oil as lubricant, the dimple phenomena in the circular EHL contacts composed of a glass disk and a steel ball were investigated experimentally with the optical interferometry technique. The traction coefficient was also measured. The experimental results were compared quantitatively with the numerical results of the corresponding thermal Newtonian EHL solutions. The comparisons show that the Newtonian thermal EHL theory can explain very well the relationship between the dimple phenomena and the slide-roll ratio, but cannot predict accurately the depth of the dimple and the magnitude of the traction coefficient. It has also been found that the Newtonian flow model overestimates the effect of the temperature-viscosity wedge and consequently, a non-Newtonian flow model may be necessary for a better understanding of the EHL dimple phenomena.

Formation of Steady Dimples in Point TEHL Contacts

2000 ◽  
Vol 123 (1) ◽  
pp. 42-49 ◽  
Author(s):  
P. Yang ◽  
S. Qu ◽  
M. Kaneta ◽  
H. Nishikawa
Keyword(s):  
Complete Solution ◽  
Elastohydrodynamic Lubrication ◽  
Experimental Results ◽  
Major Radius ◽  
Theoretical Results ◽  
Good Agreement ◽  
Contact Ellipse

Experimental results of steady dimples measured in elliptical glass-steel contact under pure sliding conditions are presented. It is found that two dimples connected with a shallower furrow are generated, each near an end of the major radius of the contact ellipse. The complete solution of the corresponding thermal elastohydrodynamic lubrication (TEHL) problem is calculated numerically. Good agreement is obtained between the experimental and theoretical results. This agreement can be explained by the temperature-viscosity wedge mechanism. Correctness of this mechanism is demonstrated using additional experiments with ceramic balls in contact with glass and sapphire disks.

Effects of transversely oriented defects and thickener lumps on grease elastohydrodynamic lubrication films

2001 ◽  
Vol 215 (3) ◽  
pp. 279-288 ◽  
Author(s):  
M Kaneta ◽  
H Nishikawa ◽  
M Naka
Keyword(s):  
Film Thickness ◽  
Contact Area ◽  
Surface Defects ◽  
Film Formation ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Optical Interferometry ◽  
Transient Behaviour ◽  
Different Types

Using the optical interferometry technique, transient behaviour of grease films at an elastrohydrodynamic lubrication (EHL) point contact caused by a transversely oriented groove and long bump passing through the contact area is directly observed with three different types of diurea grease without additives. The effects of the thickener content on the grease film formation are also examined. It has been found that the behaviour of EHL films depends strongly on the thickener structure, and the effects of surface defects on EHL films become pronounced as the film thickness decreases. It has also been found that the thickener lumps move through the EHL conjunction while repeating attachment to the surfaces and detachment from them, and the thickener lumps deposited on the surfaces affect the film behaviour as a kind of solid bump.

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