scholarly journals Lubrication Analyses of Cam and Flat-Faced Follower

Lubricants ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 31 ◽  
Author(s):  
Hazim U. Jamali ◽  
Amjad Al-Hamood ◽  
Oday I. Abdullah ◽  
Adolfo Senatore ◽  
Josef Schlattmann
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Surface Deformation ◽  
Numerical Study ◽  
Point Contact ◽  
Radius Of Curvature ◽  
Operating Cycle ◽  
Essential Step ◽  
Parabolic Shape ◽  
Principal Factors

The principal factors that affect the characteristics of contact problem between cam and follower vary enormously during the operating cycle of this mechanism. This includes radius of curvature, surface velocities and applied load. It has been found over the last decades that the mechanism operates under an extremely thin film of lubricant. Any practical improvement in the level of film thickness that separates the contacted surfaces represents an essential step towards a satisfactory design of the system. In this paper a detailed numerical study is presented for the cam and follower (flat-faced) lubrication including the effect of introducing an axial modification (parabolic shape) of the cam depth on the levels of film thickness and pressure distribution. This is achieved based on a point contact model for a cam and flat-faced follower system. The results reveal that the cam form of modification has considerable consequences on the level of predicted film thickness and pressure distribution as well as surface deformation.

Effect of changing geometrical characteristics for different shapes of a single ridge passing through elastohydrodynamic of point contacts

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohamed Abd Alsamieh
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Point Contacts ◽  
Time Step ◽  
Content Type ◽  
Geometrical Characteristics ◽  
Different Shapes

Purpose The purpose of this paper is to study the behavior of a single ridge passing through elastohydrodynamic lubrication of point contacts problem for different ridge shapes and sizes, including flat-top, triangular and cosine wave pattern to get an optimal ridge profile. Design/methodology/approach The time-dependent Reynolds’ equation is solved using Newton–Raphson technique. Several shapes of surface feature are simulated and the film thickness and pressure distribution are obtained at every time step by simultaneous solution of the Reynolds’ equation and film thickness equation, including elastic deformation. Film thickness and pressure distribution are chosen to be the criteria in the comparisons. Findings The geometrical characteristics of the ridge play an important role in the formation of lubricant film thickness profile and the pressure distribution through the contact zone. To minimize wear, friction and fatigue life, an optimal ridge profile should have smooth shape with small ridge size. Obtained results are compared with other published numerical results and show a good agreement. Originality/value The study evaluates the performance of different surface features of a single ridge with different shapes and sizes passing through elastohydrodynamic of point contact problem in relation to film thickness and pressure profile.

Three-Dimensional Temperature Distribution in EHD Lubrication: Part II—Point Contact and Numerical Formulation

1993 ◽  
Vol 115 (1) ◽  
pp. 36-45 ◽  
Author(s):  
Kyung-Hoon Kim ◽  
Farshid Sadeghi
Keyword(s):  
Temperature Distribution ◽  
Film Thickness ◽  
Numerical Study ◽  
Control Volume ◽  
Three Dimensional ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Numerical Formulation ◽  
Energy Equations

A numerical study of Newtonian thermal elastohydrodynamic lubrication (EHD) of rolling/sliding point contacts has been conducted. The two-dimensional Reynolds, elasticity and the three-dimensional energy equations were solved simultaneously to obtain the pressure, film thickness and temperature distribution within the lubricant film. The control volume approach was employed to discretize the differential equations and the multi-level multi-grid technique was used to simultaneously solve them. The discretized equations, as well as the nonorthogonal coordinate transformation used for the solution of the energy equation, are described. The pressure, film thickness and the temperature distributions, within the lubricant film at different loads, slip conditions and ellipticity parameters are presented.

Numerical Analysis of Point Contact EHL on Coated Substrates

2009 ◽  
Author(s):  
Zhan-jiang Wang ◽  
Yuan-zhong Hu ◽  
Wen-zhong Wang ◽  
Hui Wang
Keyword(s):  
Film Thickness ◽  
Surface Deformation ◽  
Contact Point ◽  
Rolling Direction ◽  
Point Contact ◽  
Hydrodynamic Pressure ◽  
Contact Problems ◽  
Surface Velocity ◽  
Influence Coefficients ◽  
Two Factors

Performances of point contact EHL on multilayered or coated substrates have been analyzed in this paper via computer simulations, with emphasis on comparing the effects of Newtonian and non-Newtonian lubricants. The lubrication system consists of a rigid ball in contact with a smooth coated flat. The coating is perfectly bonded to an elastic substrate and it has a uniform thickness. The rigid ball has surface velocity U relative to the contact point. The hydrodynamic pressure p is governed by a generalized Reynolds equation in which the non-Newtonian effects of lubricants are characterized by two factors whose values are determined based on lubricant rheology. The Papkovich-Neuber potentials were employed to get the response functions in frequency domain for layered contact problems, and the influence coefficients relating pressure to surface displacements and stresses can be obtained via invert Fourier transform. The surface deformation was then calculated in terms of the pressure-displacement influence coefficients and the DC-FFT method was used to speed up the computation. The distributions of pressure, film thickness and subsurface stress have been analyzed for lubricants with different rheological behaviors, from which pressure and film thickness profiles along the rolling direction are calculated for Newtonian and Non-Newtonian lubricants. The central film thickness become thicker for stiffer coatings in the case of Newtonian lubricants, but the trend is reversed for Non-Newtonian lubricants. The surface stresses along the rolling direction show a spike corresponding to the pressure, which is more significant with stiffer coatings in the Newtonian case, but the spike is less visible for Non-Newtonian lubricants.

Inverse Solution of Reynolds’ Equation of Lubrication Under Point-Contact Elastohydrodynamic Conditions

1981 ◽  
Vol 103 (4) ◽  
pp. 539-546 ◽  
Author(s):  
H. P. Evans ◽  
R. W. Snidle
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Inverse Solution ◽  
Heavy Loads

The paper describes a technique for solving the inverse lubrication problem under point contact elastohydrodynamic conditions, i.e. the calculation of a film thickness and shape corresponding to a given hydrodynamic pressure distribution by an inverse solution of Reynolds’ equation. The effect of compressibility and influence of pressure upon viscosity are included in the analysis. The technique will be of use in solving the point contact elastohydrodynamic lubrication problem at heavy loads.

The Minimum Film Thickness in Line Contacts During Reversal of Entrainment

1993 ◽  
Vol 115 (1) ◽  
pp. 191-199 ◽  
Author(s):  
C. J. Hooke
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Rate Of Change ◽  
Radius Of Curvature ◽  
Operating Cycle ◽  
Minimum Film Thickness ◽  
Line Contacts ◽  
Involute Gears ◽  
Shaft Seals ◽  
Steady State Predictions

In contacts, such as cams, non-involute gears and shaft seals, where the direction of entrainment reverses during the operating cycle, the minimum film thickness is typically found just after the reversal. This paper shows that this minimum film thickness is determined by the rate of change of the entraining velocity and by the fluid and surface properties. For line contacts, four regimes of lubrication are found—as for the steady-state situation—and expressions for the film thickness in each regime are developed. This enables an outline design chart for the minimum film thickness to be constructed. It is shown that this information, together with the steady-state predictions is sufficient to determine the variation of film thickness with time in most situations where load, radius of curvature, and entraining velocity vary.

Influence of Laser Micro-Mesh Texturing on the Tribological Performance in an EHL Point Contact

2007 ◽  
Vol 353-358 ◽  
pp. 796-800
Author(s):  
Xiao Wang ◽  
Jian Li ◽  
Wei Chen ◽  
Lan Cai ◽  
Jian Ying Zhu
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Point Contact ◽  
Tribological Performance ◽  
Design And Optimization ◽  
Thickness Profile ◽  
Wide Range ◽  
Key Factor

Fabricating surfaces with controlled micro-geometry may be an effective approach to improved tribological performance. In this paper, the effect of laser surface micro-mesh texturing on the tribological performance is investigated theoretically with numerical solution of EHL point contact. In the theoretical model, the Reynolds equation is used as the governing equation. Well controlled micro-mesh texturing is described in film thickness equation. By Full Multi-Grid (FMG) method, the solutions of film thickness profile and pressure distribution map are present over a wide range of texturing parameters. The influence of width, depth and orientation of mesh texturing on the friction coefficient is analyzed. Result shows that, the film thickness profile and pressure distribution are sensitive to the parameters of micro-mesh texturing. The curve result of friction coefficient under two load conditions indicated that the parameters of mesh are key factor for texturing design. Solutions demonstrate the ability of numerical simulation on the design and optimization of surface mesh texturing.

Sliding of a General Axisymmetric Point Contact

1988 ◽  
Vol 110 (3) ◽  
pp. 492-498 ◽  
Author(s):  
A. Sackfield ◽  
D. A. Hills
Keyword(s):  
Stress State ◽  
Stress Field ◽  
Pressure Distribution ◽  
Point Contact ◽  
Radius Of Curvature ◽  
First Contact

The complete stress field generated beneath an arbitrarily profiled axisymmetric indentor is found, both for normal indentation, and sliding. It is shown that a shallower profile than that of a sphere, i.e., one having a larger radius of curvature at the point of first contact, associated with a “flatter” pressure distribution, gives rise to a milder stress state, so that a heavier load may be sustained over a given contact disk without yielding.

scholarly journals Soap-Thickener Induced Local Pressure Fluctuations in a Grease-Lubricated Elastohydrodynamic Point Contact

1994 ◽  
Vol 208 (3) ◽  
pp. 191-198 ◽  
Author(s):  
H Åström ◽  
C H Venner
Keyword(s):  
Film Thickness ◽  
Surface Deformation ◽  
Pressure Fluctuations ◽  
Point Contact ◽  
Rheological Behaviour ◽  
Force Balance ◽  
Experimental Investigations ◽  
Local Pressure ◽  
Lubricated Contact ◽  
Insight Into

In several experimental investigations of grease-lubricated elastohydrodynamic (EHD) contacts indications of soap-thickener formations that enter the contact area have been reported, for example by Kageyama et al. (1), Cann and co-workers (2-4) and Åström and co-workers (5, 6). While passing through a contact such soap-thickener lumps significantly disturb the film thickness by locally increasing the surface deformation. These film-thickness fluctuations must be accompanied by pressure fluctuations, knowledge of which is essential to increase insight in the phenomena determining service life and emitted noise of grease-lubricated contacts. In this paper the authors present a combined experimental/numerical approach to generate insight into such pressure fluctuations. From a fringe pattern obtained with optical interferometry (ball-on-disc apparatus) a film-thickness map is created employing image analysis. This map serves as input to a numerical algorithm for the calculation of the pressure from force balance and elastic deformation theory. Consequently, no assumptions about the rheological behaviour of grease can be made. The method was first tested out on an oil-lubricated contact. This test gave essential insight into the accuracy of the method proposed here and in the magnitude of surface texture induced pressure fluctuations. Subsequently the approach was successfully used to estimate the pressure variations resulting from soap-thickener formations in a grease-lubricated contact (between the same ball and disc).

scholarly journals Experimental and numerical study of acoustic pressure distribution in a sonochemical reactor

2021 ◽  
Vol 1809 (1) ◽  
pp. 012025
Author(s):  
M O Kuchinskiy ◽  
T P Lyubimova ◽  
K A Rybkin ◽  
O O Fattalov ◽  
L S Klimenko
Keyword(s):  
Pressure Distribution ◽  
Acoustic Pressure ◽  
Numerical Study

scholarly journals Optical Analysis of Ball Bearing Starvation

1971 ◽  
Vol 93 (3) ◽  
pp. 349-361 ◽  
Author(s):  
L. D. Wedeven ◽  
D. Evans ◽  
A. Cameron
Keyword(s):  
Film Thickness ◽  
Ball Bearing ◽  
Point Contact ◽  
Experimental Measurements ◽  
Line Contact ◽  
Optical Analysis ◽  
Grease Lubrication ◽  
Theoretical Predictions ◽  
Pressure Stress ◽  
Starvation Conditions

Elastohydrodynamic oil film measurements for rolling point contact under starvation conditions are obtained using optical interferometry. The experimental measurements present a reasonably clear picture of the starvation phenomenon and are shown to agree with theoretical predictions. Starvation inhibits the generation of pressure and, therefore, reduces film thickness. It also causes the overall pressure, stress, and elastic deformation to become more Hertzian. Additional experiments using interferometry illustrate: the cavitation pattern, lubricant entrapment, grease lubrication, ball spin, and edge effects in line contact.

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