(Effect of surface texturing on friction under starved lubrication conditions) Fadi ALI

Transcription

1 (Effect of surface texturing on friction under starved lubrication conditions)

2 2/15 CONTENTS INTRODUCTION TITLE AND AIM OF DISSERTATION LITERATURE REVIEW BIBLIOGRAPHY METHODOLOGY PRELIMINARY RESULTS CONCLUSIONS

3 3/15 INTRODUCTION Gelinck et al Faraon et al Friction coefficient () and separation(λs) as a function of Hersey number Effect of starvation on the friction coefficient and separation

4 4/15 TITLE Effect of surface texturing on friction under starved lubrication conditions. SUPERVISOR: prof. Ing. Martin Hartl, Ph.D. AIM OF DISSERTATION Studying experimentally the effect of artificial micro-dents on reducing the coefficient of friction in sliding motion between non-conformal surfaces under starved lubrication. Comparing with results under fully flooded conditions.

5 5/15 LITERATURE REVIEW Nélias et al Effect of micro-dimples size on the pressure distribution and film thickness profile in EHL contacts. RESULTS Noeffectformallsizeofmicro-dents. Positive effect for intermediate size(no cavitation) Negative effect for large size due to the cavitation. Effect of micro-dimples size on the pressure distribution and film thickness profile

6 6/15 LITERATURE REVIEW Mourier et al Effect of micro-dimples depth RESULTS Deep micro-cavities Shallow micro-cavities enhance film thickness. Deep micro-cavities cause a reduction in film thickness. Shallow micro-cavities

7 7/15 Ai et al LITERATURE REVIEW Effect of slide-to-roll ratio (SR). RESULTS Limited effect under pure rolling conditions. Positive effect when the sliding is introduced. SR=0 SR=2

8 8/15 LITERATURE REVIEW Effect of micro-dents on rolling contact fatigue (RCF) Coulon et al Nélias et al RESULTS Low stress concentration was found under pure rolling. Slide-to-roll ratio increases thestresslevel. Location of concentrated pressure depends on the direction of sliding. Pressure profiles for smooth and dented contact stress field in the vicinity of micro-dent

9 9/15 LITERATURE REVIEW Dumont et al Effect of micro-dimpling under starved conditions. RESULTS The beneficial increase of film thickness is lost if the contact becomes fully flooded. a) Fully flooded contact b) Starved contact Damiens et al Film thickness under starved lubrication

10 10/15 Effect of surface textures on BIBLIOGRAPHY pressure distribution and film thickness profile in EHL contacts: Coefficient of friction under starved conditions: COULON,S.etal.2004 MOURIER, L. et al. 2006, FARAON, I.C. AND SCHIPPER, 2008,2010 D.J. 2006,2007 WEDEVEN, L.D. et al.1979 Querliozetal.2007 Cusano,C.etal.1981 Yang,P.etal.2004 Surface textures of conformal Kaneta,M.etal.1997 surfaces: AI,X.L.etal1994,1996 Lubrecht A.A Etsion et al. 1999, 2002,2009. KRUPKA, I. et al. 2007, NANBU et al ,2010

11 11/15 BIBLIOGRAPHY Starved lubrication: DAMIENS,B.etal.2004 OLARU,D.N.etal.1993 CHEVALIER, F. et al.1998 WEDEVEN,L.D.etal1971 GHOSH,M.K.etal.1987 Effect of Surface texture on contact fatigue: CHENG,W. et al Zhai X, et al Ai X. et al. 1996,2000,2001 NELIAS, D. et al 2000 Surface feature effect under starved lubrication: DUMONT,M.etal.2002

12 12/15 METHODOLOGY MTM(Mini Traction Machine) Torque sensor in combination with optical interferometry

13 Presentation of Dissertation 13 / Smooth Textured Load=32N, SRR=-1,starved 14µL Coefficient of friction 0.11 PRELIMINARY RESULTS 0.12 Load=32N Entraining velocity Ue=30 [mm/s] Slide-to-roll ratio SRR= Time [min] 0.1 coefficient of friction of smooth and dented surfaces under starved lubrication Smooth Textured Load=32N, SRR=-1,fully flooded Time [min] Effect of Starvation on the coefficient of friction Coefficient of friction Coefficient of friction Starved 14µL Starved 18µL Starved 42µL Fully-flooded Time [min] coefficient of friction of smooth and dented surfaces under fully flooded lubrication

14 14/15 CONCLUSIONS The value of friction coefficient under starved lubrication is strongly influenced by the position of air-oil meniscus from the center of Hrtzian contact. The effect of shallow micro-dents on the friction coefficient is negligible under fully flooded conditions. Shallow micro-dents can help in reducing the friction coefficient under starved lubrication.

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