Model rough surfaces in elastohydrodynamic lubrication

1982 ◽  
Vol 96 (1) ◽  
pp. 1-8 ◽  
Author(s):  
S. De Silva ◽  
J.C. Anderson ◽  
J.A. Leather
Keyword(s):  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication

scholarly journals Understanding the Mechanism of Load-Carrying Capacity between Parallel Rough Surfaces through a Deterministic Mixed Lubrication Model

Lubricants ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 12
Author(s):  
Yuechang Wang ◽  
Abdullah Azam ◽  
Gaolong Zhang ◽  
Abdel Dorgham ◽  
Ying Liu ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Stribeck Curve ◽  
Future Research ◽  
Load Carrying Capacity ◽  
Proposed Model ◽  
Load Carrying ◽  
Lift Off

Experimental results have confirmed that parallel rough surfaces can be separated by a full fluid film. However, such a lift-off effect is not expected by the traditional Reynolds theory. This paper proposes a deterministic mixed lubrication model to understand the mechanism of the lift-off effect. The proposed model considered the interaction between asperities and the micro-elastohydrodynamic lubrication (micro-EHL) at asperities within parallel rough surfaces for the first time. The proposed model is verified by predicting the measured Stribeck curve taken from literature and experiments conducted in this work. The simulation results highlight that the micro-EHL effect at the asperity scale is critical in building load-carrying capacity between parallel rough surfaces. Finally, the drawbacks of the proposed model are addressed and the directions of future research are pointed out.

Efficient running-in of gears and improved prediction of the tooth flank load carrying capacity

2019 ◽  
Vol 71 (3) ◽  
pp. 366-373
Author(s):  
Martin Zimmer ◽  
Dirk Bartel
Keyword(s):  
Carrying Capacity ◽  
Plastic Material ◽  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Load Carrying ◽  
Life Model ◽  
Extended Life ◽  
Tooth Flank

Purpose The purpose of this paper is to determine parameters for an efficient running-in of gears and an improved method for the prediction of the tooth flank load carrying capacity. Design/methodology/approach In this contribution, a model for the calculation of the pitting life of involute spur gears is introduced, which is based on an extension of the life model according to Ioannides and Harris for rough surfaces. To achieve the most realistic thermal elastohydrodynamic lubrication simulation and stress calculation possible, measured real surfaces and elastic-plastic material properties of the area close to the surface are used. Special attention is paid to the compatibility of the fatigue life calculation for heterogeneous rough surfaces and their consistent consideration in the lifespan calculation. Findings A non-destructive running-in for twin-disc pairings can be performed using suitable operating parameters, which subsequently can be transferred to tooth flank tests. Using the extended life model according to Ioannides and Harris, an enhanced prediction of the tooth flank load carrying capacity is possible. Originality/value The developed extended life model includes a new numerical approach for calculating the tooth flank load carrying capacity. It has the potential to reliably support and hence to accelerate the design process of gears.

Point Contact EHL Based on Optically Measured Three-Dimensional Rough Surfaces

1997 ◽  
Vol 119 (3) ◽  
pp. 375-384 ◽  
Author(s):  
Dong Zhu ◽  
Xiaolan Ai
Keyword(s):  
Rough Surface ◽  
Rough Surfaces ◽  
Three Dimensional ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Peak Height ◽  
Machining Process ◽  
Maximum Pressure ◽  
Pressure Peak ◽  
Surface Profiles

This paper presents a numerical solution for the elastohydrodynamic lubrication in point contacts, using optically measured three-dimensional rough surface profiles as input data. The multi-grid computer program originally developed by Ai and Cheng (1993, 1994) is modified, so that both contacting surfaces can be three-dimensional measured rough surfaces moving at different velocities. Many different engineering surfaces are measured and analyzed in the present study, demonstrating that the numerical analysis is practical for real surfaces of bearings, cams, gears and other components, as long as a significant EHL film still exists. In addition, discussions are given in this paper for the effects of three-dimensional rough surface topography, which is related to machining process. It appears that, for the circular contact cases analyzed, surface roughness texture and orientation do not have a significant effect on the average film thickness, but they do affect the maximum pressure peak height and asperity deformation in the contact zone considerably.

The Influence of the Roughness Parameters on the EHL Line Contact Using the Free Volume Model

2013 ◽  
Author(s):  
V. D’Agostino ◽  
V. Petrone ◽  
A. Senatore
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Free Volume ◽  
Rough Surfaces ◽  
Random Number Generator ◽  
Elastohydrodynamic Lubrication ◽  
Maximum Pressure ◽  
Line Contact ◽  
Volume Viscosity ◽  
Minimum Film Thickness

A numerical solution of elastohydrodynamic lubrication (EHL) contact between two rough surface cylinders is presented. In the theoretical approach the free-volume viscosity model is used to describe the piezo-viscous behavior of the lubricant in a Newtonian Elastohydrodynamic line contact [1,2]. Random rough surfaces with Gaussian and exponential statistics have been generated using a method outlined by Garcia and Stoll [3], where an uncorrelated distribution of surface points using a random number generator is convolved with a Gaussian filter to achieve correlation. This convolution is most efficiently performed using the discrete Fast Fourier Transform (FFT) algorithm, which in MATLAB is based on the FFTW library [4]. The maximum pressure and average film thickness are studied at different values of RMS, skewness, kurtosis, autocorrelation function and correlation length. Numerical examples show that skewness and kurtosis have a great effect on the parameters of EHD lubrication. Surface roughness, indeed, tends to reduce the minimum film thickness and it produces pressure fluctuations inside the conjunction which tend to increase the maximum stress. In this way the dynamic stress increases and tends to reduce the fatigue life of the components. It can be seen that the pressures developed in the fluid film in the case of rough surfaces fluctuate with the same frequency of the surface roughness. These pressure ripples correspond to the asperity peaks. This indicates that surface roughness causes very high local contact pressures which may lead to local thinning of the film. A significant reduction has been also observed in the minimum film thickness due to surface roughness.

scholarly journals Effective Implementation of Elastohydrodynamic Lubrication of Rough Surfaces into Multibody Dynamics Software

2021 ◽  
Vol 11 (4) ◽  
pp. 1488
Author(s):  
Jozef Dlugoš ◽  
Pavel Novotný
Keyword(s):  
Multibody Dynamics ◽  
Degrees Of Freedom ◽  
Combustion Engine ◽  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication ◽  
Shape Reconstruction ◽  
General Purpose ◽  
Dynamics Simulation ◽  
Computational Time ◽  
Dynamics Simulations

Currently, multibody dynamics simulations are moving away from issues exclusive to dynamics to more multiphysical problems. Most mechanical systems contain contact pairs that influence the dynamics of the entire mechanism, such as friction loss, wear, vibration and noise. In addition, deformation often affects the interaction between the contact bodies. If that is the case, this effect must be considered. However, a major disadvantage arises in that it leads to an increase in the number of degrees of freedom and the computational time. Often, the general-purpose multibody dynamics software does not take into account advanced phenomena, such as a lubricated contact pair. This paper can serve as a guide to implementing the elastohydrodynamic lubrication of rough surfaces into general-purpose multibody dynamics software (in this case MSC Adams), which remains challenging. In this paper, the deformation shape reconstruction of the reduced flexible bodies is described, as well as a solution to the increase in the computational speed issues thereby caused. To alleviate this burden, advanced sensitivity analysis techniques are used. In this paper, parallel computing has been employed. The proposed method leads to reasonable computational times for the multibody dynamics simulations, including elastohydrodynamic lubrication. The proposed method is applied to the multibody dynamics simulation of the piston–liner interaction of an internal combustion engine.

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