Problematika disertační práce a současný stav řešení I never worry about the future. It comes soon enough Albert Einstein
2 /12 CONTENTS Topic of thesis and objectives Introduction Background of problem Experimental equipment and related problems Current state of solution Next stages of work
3 /12 TOPIC OF THESIS: Design of Traction Machine SUPERVISOR: prof. Ing. Martin Hartl, Ph.D. SUPERVISOR ASSISTANT: prof. Ing. Ivan Křupka, Ph.D. OBJECTIVES: Setting Stribeck curves (coefficient of friction) for smooth and textured non-conformal surfaces in relative motion to analyze the effect of surface texturing on the coefficient of friction.
4 /12 INTRODUCTION Stribeck Curve represents the coefficient of friction (µ) as a function of many parameters. coefficient of friction (µ) for EHD point contact: QUESTION What is the effect of surface texturing on the coefficient of friction for lubricated non-conformal surfaces? http://www.pcs-instruments.com/
5 /12 BACKGROUND OF PROBLEM STRIBECK CURVE FOR LUBRICATED CONTACTS E.R.M. Gelinck.Calculation of Stribeck curves for line contacts,2000 D. J. Schipper.Stribeck Curve for Starved Line Contacts,2007 Xiaobin Lu.The Stribeck Curve: Experimental Results and Theoretical Prediction Surface texturing for lubricated contacts,2006 SURFACE TEXTURING FOR LUBRICATED CONTACTS Leiming Gao.Effect of surface texturing on the elastohydrodynamic lubrication analysis of metal-on-metal hip implants,2010 L. Mourier.Transient increase of film thickness in micro-textured EHL contacts,2006 Toshikazu Nanbu. Micro-Textures in Concentrated Conformal-Contact Lubrication: Effects of Texture Bottom Shape and Surface Relative Motion,2008 Alexey Shinkarenkoa.Theoretical Analysis of Surface-Textured Elastomer Sleeve in Lubricated Rotary Sliding,2010
6 /12 BACKGROUND OF PROBLEM STRIBECK CURVE FOR DIMPLED SURFACES Manabu Wakuda.Effect of surface texturing on friction reduction between ceramic and steel materials under lubricated sliding contact,2002 Xiaobin Lu.An Experimental Investigation of Dimple Effect on the Stribeck Curve of Journal Bearings,2007 Lidia Galda.Dimples shape and distribution effect on characteristics of Stribeck curve,2009 Fanming Meng.Study on effect of dimples on friction of parallel surfaces under different sliding conditions,2010 S. Akbarzadeh.Effect of Surface Pattern on Stribeck Curve,2010 A. Erdemir.Review of engineered tribological interfaces for improved boundary lubrication,2005
7 /12 EXPERIMENTAL EQUIPMENT AND RELATED PROBLEMS Load(Fn) Disc Torque (Mt) Torque Sensor Friction force(ft) Ball Calculation of friction coefficient(μ): Ft=2*Mt/Dball μ = Ft/Fn D/A Card PC
Torque[N.mm] Mean values Torque[N.mm] Problematika disertační práce a současný stav řešení 8 /12 EXPERIMENTAL EQUIPMENT AND RELATED PROBLEMS Deviation of measured signal Determination of reference point 7 6 5 Determination of initial conditions (load =0,speed =0) 4 3 2 1 Deviation of signal at speed 100[RPM],load13[N] Deviation of signal at speed 66.6[RPM],load13[N] Deviation of signal at speed 33.3[RPM],load13[N] 0 0 5 10 15 Time[sec] Torque Mt=0 NO Correction and calibration LabVIEW 7 Yes 6 5 End 4 3 2 1 Deviation of signal at speed 100[RPM],load13[N] Deviation of signal at speed 66.6[RPM],load13[N] Deviation of signal at speed 33.3[RPM],load13[N] 0 0 5 10 15 Time[sec]
Friction force[n] Coefficient of friction Problematika disertační práce a současný stav řešení 9 /12 CURRENT STATE OF SOLUTION Measuring the friction force Measuring the coefficient of friction 0.8 0.6 Load 8[N] Load13[N] 0.1 0.08 Load 13[N] simulating Load 8[N] simulating 0.06 0.4 0.04 0.2 0.02 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 U[m/s] 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 U[m/s]
Coefficent of Traction Coefficient of friction Problematika disertační práce a současný stav řešení 10 /12 CURRENT STATE OF SOLUTION 0.16 0.14 load13[n],ud=-10rpm Simulating 0.12 Coefficient of friction in case of negative rotation of disc. Sliding velocity: Us= Ub-Ud 0.1 0.08 0.06 0.04 0.02 0.05 0 0 0.05 0.1 0.15 0.2 Us [m/s] 0.04 Measuring the traction coefficient slide=2*(ub-ud)/ (Ub+Ud) 0.03 0.02 0.01 Experimental,Load13[N] Simulating 0 0 10 20 30 40 50 60 70 slide%
11 /12 NEXT STAGES OF WORK Measuring the coefficient of friction for textured (dimpled ) non-conformal surfaces in relative motion. Making a comparison with the coefficient of friction for smooth surfaces. Contact without texturing Discussing the results. Writing articles Contact with texturing
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