Direct simulation of fluid lubricated contacts down to the surface roughness scale

2016 ◽  
Author(s):  
Hugo Checo ◽  
Alfredo Jaramillo ◽  
Roberto Ausas ◽  
Mohammed Jai ◽  
Gustavo Buscaglia
Keyword(s):  
Surface Roughness ◽  
Direct Simulation ◽  
Lubricated Contacts

Rapid calculation of the pressures and clearances in rough, rolling-sliding elastohydrodynamically lubricated contacts. Part 1: Low-amplitude, sinusoidal roughness

2007 ◽  
Vol 221 (5) ◽  
pp. 535-549 ◽  
Author(s):  
C J Hooke ◽  
K Y Li ◽  
G Morales-Espejel
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Perturbation Analysis ◽  
Curve Fitting ◽  
Calculation Method ◽  
The Third ◽  
Lubricated Contacts ◽  
Rapid Calculation ◽  
Low Amplitude ◽  
Rough Rolling

Surface roughness in elastohydrodynamically lubricated (EHL) contacts may have a significant effect on component life and there is a need to be able to assess its effects quickly. This article describes a rapid calculation method, which provides accurate results where the amplitude of the roughness is relatively low and which gives good indications of the likely behaviour for higher amplitudes. In the first part, the effect of low-amplitude, sinusoidal roughness is examined, and it is shown that the behaviour can, for any wavelength and roughness orientation, be characterized by three complex quantities. Calculation of two of these is straightforward; the third requires curve fitting to the results obtained using a perturbation analysis. Details of the process are given. The second part of the article discusses how these results can be used to predict the behaviour of any rough surface under rolling-sliding EHL conditions.

Numerical Simulation of Elastohydrodynamically Lubricated Contacts With Rough Surfaces

1994 ◽  
Vol 47 (6S) ◽  
pp. S221-S227 ◽  
Author(s):  
Alan Xiaolan Ai ◽  
Herbert S. Cheng
Keyword(s):  
Numerical Simulation ◽  
Surface Roughness ◽  
Numerical Analysis ◽  
Convective Flow ◽  
Multigrid Method ◽  
Rough Surfaces ◽  
Point Contacts ◽  
Random Roughness ◽  
Lubricated Contacts ◽  
Lubricant Flow

Transient numerical analysis to elastohydrodynamically lubricated point contacts with rough surfaces is described. The numerical simulation is based on the multigrid method. Three types of surface roughness: single dent or bump, oblique waviness and random roughness are reviewed. Under heavily loaded conditions, results reveal a strong domination of Couette flow (convective flow). The presence of sliding greatly increases pressure fluctuation and as a consequence may lead to surface-initiated spallings. For obliquely orientated roughness, lubricant flow intends to deform the ridges and create primarily longitudinal passages.

Rapid Calculation of the Pressures and Clearances in Rough, Elastohydrodynamically Lubricated Contacts Under Pure Rolling. Part 1: Low Amplitude, Sinusoidal Roughness

2006 ◽  
Vol 220 (6) ◽  
pp. 901-913 ◽  
Author(s):  
C J Hooke ◽  
K Y Li
Keyword(s):  
Surface Roughness ◽  
Real Time ◽  
Design Process ◽  
Design Tool ◽  
Operating Conditions ◽  
Lubricated Contacts ◽  
Pure Rolling ◽  
Rapid Calculation ◽  
Low Amplitude ◽  
Insight Into

Modern elastohydrodynamically lubricated (EHL) solvers allow the calculation of the pressures and clearances in rough EHL contacts. However, the process is time consuming and the results give little insight into the physical behaviour of the system. The length of calculation also makes these methods unsuitable for use as a design tool. The investigation of the behaviour of low amplitude, sinusoidal roughness in EHL contacts provides greater understanding of the processes involved. The results also allow the effects of surface roughness to be examined rapidly. This suggests that it may be possible to develop the approach and create a ‘real-time’ design process for the analysis of different surface roughnesses under a range of operating conditions.

Pressure and Shear Flow Factors Calculation for Orthotropic Rough Surfaces

2007 ◽  
Author(s):  
Ramona Dragomir ◽  
Dominique Bonneau ◽  
Patrick Ragot ◽  
Franc¸ois Robbe-Valloire
Keyword(s):  
Surface Roughness ◽  
Shear Flow ◽  
Reynolds Equation ◽  
Rough Surfaces ◽  
Cross Flow ◽  
Lubricated Contacts ◽  
General Average ◽  
The Cross

In general, average Reynolds equation is defined in terms of shear flow factors in order to determine the effects of surface roughness on partially lubricated contacts. This paper is essentially devoted to the application of flow factors model to real shaft and bearing surfaces, obtained by metrological measures. Additionally, the average Reynolds equation is completed by “cross” flow factors. The “cross” flow factors may have an important role if model is applied on either longitudinally or transversely oriented surfaces (surfaces with directional patterns oriented with an angle).

Influence of Surface Roughness on Traction and Scuffing Performance of Lubricated Contacts for Aerospace and Automotive Gearing

2012 ◽  
Author(s):  
Sam Shon ◽  
Ahmet Kahraman ◽  
Kelsen LaBerge ◽  
Brian Dykas ◽  
David Stringer
Keyword(s):  
Surface Roughness ◽  
Operating Conditions ◽  
Test Set ◽  
Lubricated Contacts ◽  
Gear Steel ◽  
Steel Aisi ◽  
Set Up ◽  
The Impact ◽  
Disk Test

In this study, a two-disk test set-up was employed to investigate the impact of surface roughness on the performance of lubricated contacts. In an attempt to simulate contacts from automotive transmissions and rotorcraft gearboxes, roller specimens made of a typical automotive gear steel (AISI 5120) and a common rotorcraft gear steel (AISI 9310) were paired with 80W90 and MIL-PRF23699 lubricants, respectively. The specimens were subjected to various operating conditions to measure their traction and scuffing outcome (i) axially ground, (ii) chemically polished isotropic surfaces, and (iii) highly polished mirror-like surfaces.

Static or breakloose friction for lubricated contacts: the role of surface roughness and dewetting

2013 ◽  
Vol 25 (44) ◽  
pp. 445013 ◽  
Author(s):  
B Lorenz ◽  
B A Krick ◽  
N Rodriguez ◽  
W G Sawyer ◽  
P Mangiagalli ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Lubricated Contacts
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