Effect of Surface Roughness on the Point Contact EHL

1988 ◽  
Vol 110 (1) ◽  
pp. 32-37 ◽  
Author(s):  
D. Zhu ◽  
H. S. Cheng
Keyword(s):  
Reynolds Equation ◽  
Point Contact ◽  
Roughness Parameter ◽  
Elastohydrodynamic Lubrication ◽  
Surface Pattern ◽  
Roughness Parameters ◽  
Elasticity Equation ◽  
Asperity Contacts ◽  
Surface Irregularities ◽  
Effect Of Surface

In this paper a full numerical solution for the partial elastohydrodynamic lubrication in elliptical contacts is presented, and the procedure of computation is briefly described. The average Reynolds equation developed by Patir and Cheng, the elasticity equation, and the pressure-viscosity relationship are solved simultaneously. The asperity contacts are also taken into account by using the model contributed by Greenwood and Tripp. The distribution of surface irregularities is assumed to be Gaussian. The effects of various roughness parameters on the film thickness are investigated. Special attention is given to the surface pattern parameter and hydrodynamic roughness parameter.

Influence of Surface Roughness and Its Orientation on Partial Elastohydrodynamic Lubrication of Rollers

1983 ◽  
Vol 105 (4) ◽  
pp. 591-597 ◽  
Author(s):  
J. Prakash ◽  
H. Czichos
Keyword(s):  
Reynolds Equation ◽  
Complete Solution ◽  
Elastohydrodynamic Lubrication ◽  
Coupled System ◽  
Line Contact ◽  
Roughness Parameters ◽  
Regime Changes ◽  
Lubrication Regime ◽  
Elasticity Equation ◽  
The Stability

In this paper, a complete solution for a rough, isothermal elastohydrodynamic line contact operating in the partial lubrication regime is presented. The semianalytical EHD line contact model developed recently [12], is used in solving the coupled system of average Reynolds equation and the elasticity equation. The effects of various operating parameters and the roughness parameters are investigated with an emphasis on the outlet behavior. The results indicate that in the partial lubrication regime changes in the outlet may play an important role on the stability of elastohydrodynamic films.

Multigrid method for the solution of EHL point contact with bio-based oil as lubricants for smooth and rough asperity

2018 ◽  
Vol 70 (4) ◽  
pp. 599-611 ◽  
Author(s):  
Vishwanath B. Awati ◽  
Shankar Naik ◽  
Mahesh Kumar N.
Keyword(s):  
Design Methodology ◽  
Reynolds Equation ◽  
Multigrid Method ◽  
Approximation Scheme ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Alternative Source ◽  
Content Type ◽  
Longitudinal Roughness ◽  
Isothermal Case

Purpose The purpose of this paper is to study the elastohydrodynamic lubrication point contact problem with bio-based oil as lubricants for an isothermal case. The simulation of the problem is analyzed on smooth and rough asperity. Design/methodology/approach The modified Reynolds equation is discretized using finite difference and multigrid method with full approximation scheme (FAS), applied for its solution with varying load and speed. Findings This paper traces out the comparison of minimum and central film thickness with the standard formulation of Hamrock and Dowson. The effect of longitudinal roughness on surfaces is investigated by means of numerical simulations. Originality/value The results obtained are comparable with the standard results, and are shown by graphs and tables. Bio-based products bring out an alternative source of lubricant to reduce energy crises.

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.

The Isothermal Elastohydrodynamic Lubrication of Spheres

1981 ◽  
Vol 103 (4) ◽  
pp. 547-557 ◽  
Author(s):  
H. P. Evans ◽  
R. W. Snidle
Keyword(s):  
Iterative Method ◽  
Reynolds Equation ◽  
Point Contact ◽  
Numerical Procedure ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Operating Conditions ◽  
Analysis Of Results ◽  
Approximate Formulas ◽  
Pressure Analysis

The paper describes a numerical procedure for solving the point-contact elastohydrodynamic lubrication problem under isothermal conditions at moderate loads. Results are presented showing the shape of the film and variation of hydrodynamic pressure. Analysis of results for a range of operating conditions gives the following approximate formulas for minimum and central film thickness, repsectively: Hm = 1.9 M−0.17 L0.34 and Ho = 1.7 M−0.026 L0.40 where H, M, and L are the Moes and Bosma nondimensional groups. In common with earlier solutions based upon the forward-iterative method the solution breaks down under moderately heavily loaded conditions. Ways of extending the solution to heavier loads using the authors’ inverse solution of Reynolds’ equation under point-contact elastohydrodynamic conditions are discussed.

A mixed elastohydrodynamic lubrication model based on virtual rough surface for studying the tribological effect of asperities

2018 ◽  
Vol 70 (2) ◽  
pp. 408-417 ◽  
Author(s):  
Hui Zhang ◽  
Guangneng Dong ◽  
Guozhong Dong
Keyword(s):  
Film Thickness ◽  
Rough Surface ◽  
Current Model ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Surface Pattern ◽  
Curvature Radius ◽  
Content Type ◽  
Stribeck Curves ◽  
Effect Of Surface

Purpose The main purpose of this paper is to present the effort on developing a mixed elastohydrodynamic lubrication (EHL) model to study the tribological effect of asperities on rough surface. Design/methodology/approach The model, with the use of the average flow Reynolds equation and the K-E elasto-plastic contact model, allows predictions of hydrodynamic pressure and contact pressure on the virtual rough surface, respectively. Then, the substrate elastic deformation is calculated by discrete convolution fast-Fourier transform (DC-FFT) method to modify the film thickness recursively. Afterwards, corresponding ball-on-disk tests are conducted and the validity of the model demonstrated. Moreover, the effects of asperity features, such as roughness, curvature radius and asperity pattern factor, on the tribological properties of EHL, are also discussed though plotting corresponding Stribeck curves and film thickness shapes. Findings It is demonstrated that the current model predicts very close data compared with corresponding experimental results. And it has the advantage of high accuracy comparing with other typical models. Furthermore, smaller roughness, bigger asperity radius and transverse rough surface pattern are found to have lower friction coefficients in mixed EHL models. Originality/value This paper contributes toward developing a mixed EHL model to investigate the effect of surface roughness, which may be helpful to better understand partial EHL.

Elastohydrodynamic lubrication of a circular point contact for a compliant layered surface bonded to a rigid substrate Part 1: Theoretical formulation and numerical method

2000 ◽  
Vol 214 (3) ◽  
pp. 267-279 ◽  
Author(s):  
Z. M. Jin
Keyword(s):  
Numerical Method ◽  
Reynolds Equation ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Contact Radius ◽  
Rigid Substrate ◽  
Theoretical Formulation ◽  
Circular Point ◽  
Present Solution ◽  
Raphson Method

A full numerical analysis of the elastohydrodynamic lubrication problem of a circular point contact involving a compliant layered surface firmly bonded to a rigid substrate is reported in the present study. The Reynolds equation has been solved simultaneously with the full elasticity equation for the layered bearing surface under entraining motion, using the Newton-Raphson method. The theoretical formulation and the numerical method are presented in the present paper (Part 1), together with the comparison of the predicted minimum and central film thickness between the present solution when the contact radius is much smaller than the layer thickness and the results for a semi-infinite solid reported in the literature.

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.

Elastohydrodynamic Lubrication of Circumferentially Finished Rollers having Sinusoidal Roughness

1987 ◽  
Vol 201 (1) ◽  
pp. 29-36 ◽  
Author(s):  
G Karami ◽  
H P Evans ◽  
R W Snidle
Keyword(s):  
Film Thickness ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Axial Direction ◽  
Constant Load ◽  
Asperity Contact ◽  
Asperity Contacts ◽  
Roughness Amplitude ◽  
Large Roughness

The paper describes an isothermal elastohydrodynamic lubrication analysis of rollers having circumferential sinusoidal roughness. Theoretical results are shown which demonstrate the influence of roughness amplitude on the distribution of hydrodynamic pressure and film thickness at constant load and constant roughness wavelength. At a large roughness amplitude the hydrodynamic pressure in the valleys between asperity contacts is insignificant and each asperity contact behaves as an ‘isolated’ elastohydrodynamic point contact. As the roughness is reduced, however, the valley pressures build up, the pressure becomes more uniformly distributed in the axial direction and the minimum film thickness increases.

Isothermal Elastohydrodynamic Lubrication of Point Contacts: Part 1—Theoretical Formulation

1976 ◽  
Vol 98 (2) ◽  
pp. 223-228 ◽  
Author(s):  
B. J. Hamrock ◽  
D. Dowson
Keyword(s):  
Numerical Analysis ◽  
Entire Range ◽  
Reynolds Equation ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Uniform Pressure ◽  
Point Contacts ◽  
Elasticity Analysis ◽  
Simultaneous Solution ◽  
Theoretical Formulation

The analysis of an isothermal elastohydrodynamic lubrication (EHL) point contact was evaluated numerically. This required the simultaneous solution of the elasticity and Reynolds equations. In the elasticity analysis the contact zone is divided into equal rectangular areas and it is assumed that a uniform pressure is applied over each element. In the numerical analysis of the Reynolds’ equation a phi analysis where phi is equal to the pressure times the film thickness to the 3/2 power is used to help the relaxation process. The EHL point contact analysis is applicable for the entire range of elliptical parameters and is valid for any combination of rolling and sliding within the contact.

scholarly journals Internal surface roughness of plastic pipes for irrigation

2017 ◽  
Vol 21 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Hermes S. da Rocha ◽  
Patricia A. A. Marques ◽  
Antonio P. de Camargo ◽  
José A. Frizzone ◽  
Ezequiel Saretta
Keyword(s):  
Surface Roughness ◽  
Roughness Parameter ◽  
Internal Surface ◽  
Low Density Polyethylene ◽  
Pipe Diameter ◽  
Roughness Parameters ◽  
Pressure Losses ◽  
Plastic Pipes ◽  
Irrigation Pipes ◽  
Surface Irregularities

ABSTRACT Assuming that a roughness meter can be successfully employed to measure the roughness on the internal surface of irrigation pipes, this research had the purpose of defining parameters and procedures required to represent the internal surface roughness of plastic pipes used in irrigation. In 2013, the roughness parameter Ra, traditional for the representation of surface irregularities in most situations, and the parameters Rc, Rq, and Ry were estimated based on 350 samples of polyvinyl chloride (PVC) and low-density polyethylene (LDPE) pipes. Pressure losses were determined from experiments carried out in laboratory. Estimations of pressure loss varied significantly according to the roughness parameters (Ra, Rc, Rq, and Ry) and the corresponding pipe diameter. Therefore, specific values of roughness for each pipe diameter improves accuracy in pressure losses estimation. The average values of internal surface roughness were 3.334 and 8.116 μm for PVC and LDPE pipes, respectively.

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