Elastohydrodynamic Lubrication of Multiple Periodic Ridges

Author(s):  
A. V. Olver ◽  
R. Glovnea ◽  
J.-W. Choo ◽  
H. A. Spikes

The lubrication of rolling contacts in which one surface has a roughness consisting of periodic transverse or longitudinal ridges has been widely investigated, both theoretically, by, for example, Venner, Lubrecht, Greenwood, Snidle and Evans [1–4] and by means of experiments [5–7]. The problem is relevant to the lubrication of machined surfaces which have a strong periodic element of roughness.

Author(s):  
A. V. Olver ◽  
D Dini

A difficulty with the standard fast Fourier transform (FFT) perturbation model of roughness in lubricated rolling contacts is that it does not necessarily converge towards the elastic case as the film thickness is reduced; rather it leads to a situation in which all the roughness is completely flattened. This is rarely the case for real engineering surfaces. Here, it is shown that this difficulty can be avoided by carrying out a Fourier transform of the elastostatically flattened roughness and using the resulting (complex) amplitude as the low-film thickness limit of each Fourier component in the elastohydrodynamic lubrication (EHL) analysis. Results give a plausible convergence to the elastostatic solution, which is nevertheless consistent with the expected near-full-film EHL behaviour and which becomes identical to the earlier model for roughness that, statically, can be fully flattened. As expected, hydrodynamic action persists at the finest scale, even for very thin films.


2020 ◽  
Vol 40 (10) ◽  
pp. 822-825
Author(s):  
N. M. Rasulov ◽  
U. M. Nadirov ◽  
M. Z. Alekberov
Keyword(s):  

2021 ◽  
Author(s):  
Yong Zheng ◽  
Changqing Wang ◽  
Chao Pu ◽  
Jiayu Gong ◽  
Fanming Meng

2015 ◽  
Vol 647 ◽  
pp. 188-194
Author(s):  
Břetislav Skrbek

The porosity is unwanted phenomenon mostly that is tried to eliminate. The pores are initiation site of fatigue fractions usually, they worse strength and ductility of materials, quality of machined surfaces and their following surface treatment.


Author(s):  
Armando Félix Quiñonez ◽  
Guillermo E Morales Espejel

This work investigates the transient effects of a single subsurface inclusion over the pressure, film thickness, and von Mises stress in a line elastohydrodynamic lubrication contact. Results are obtained with a fully-coupled finite element model for either a stiff or a soft inclusion moving at the speed of the surface. Two cases analyzed consider the inclusion moving either at the same speed as the mean velocity of the lubricant or moving slower. Two additional cases investigate reducing either the size of the inclusion or its stiffness differential with respect to the matrix. It is shown that the well-known two-wave elastohydrodynamic lubrication mechanism induced by surface features is also applicable to the inclusions. Also, that the effects of the inclusion become weaker both when its size is reduced and when its stiffness approaches that of the matrix. A direct comparison with predictions by the semi-analytical model of Morales-Espejel et al. ( Proc IMechE, Part J: J Engineering Tribology 2017; 231) shows reasonable qualitative agreement. Quantitatively some differences are observed which, after accounting for the semi-analytical model's simplicity, physical agreement, and computational efficiency, may then be considered as reasonable for engineering applications.


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