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TRIBOLOGY , Its Possibility and Impossibility Yoshitsugu Kimura KAGAWA UNIVERSITY.

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Presentation on theme: "TRIBOLOGY , Its Possibility and Impossibility Yoshitsugu Kimura KAGAWA UNIVERSITY."— Presentation transcript:

1 TRIBOLOGY , Its Possibility and Impossibility Yoshitsugu Kimura KAGAWA UNIVERSITY

2 ・ Heavy industry to IT-related Industry ・ Restructuring in Industry Recent Changes in Social Conditions Around TRIBOLOGY → Micro-, Nano-scale Tribology → Decrease in the Number of Tribologists

3 What is Expected of TRIBOLOGY and What Can We Do in the Future? ・ Predictability ・ Controllability ・ Profitability

4 Predictability -Importance of accurate prediction ・ An earthquake M7.0 in greater Tokyo area would cause economic losses of 41×10 12 JPYen. ・ Economic losses due to stopping production for 1 day in the area would amount to 0.4×10 12 JPYen.

5 Accuracy of Prediction in Hydrodynamic Lubrication Depends upon …… Factors to be included in analyses Elastic deformation Temperature / Pressure effects Transition phenomena, etc. Limitation on computation Models expecting increase in computation speed

6 Factors Impairing Accuracy of Prediction During Boundary/Dry Sliding ・ Form and dimensional errors ・ Surface irregularities ・ Surface contamination ・ Material contamination ・ Changes in these with operation

7 Controllability -Changes in the requirement for Tribology ・ Reduction of friction alone ・ Prevention of surface damage → Maintaining friction in certain ranges → Maintaining wear rates in certain ranges??

8 Control of Friction -Control of normal load or friction coefficient Passive control Active control ・ Selecting Lubricants ・ Mechanical Design ・ Materials ・ Using active feedback elements or ……

9 Possibility of Active Control With Liquid Crystal Lubricant By applying electric field …… ・ Change in apparent viscosity ・ Change in friction in boundary lubrication → Control of friction in hydro- dynamic lubrication

10 Another Important Issue - Control of Deterioration ・ Changes in form and dimension, micro-geometry, surface films, subsurface layers; contamination of lubricant, depletion of additives, additives, etc. ・ Sensing and preventing, or compensating for, those changes

11 -Tribologists should show profitability of tribology, quantitatively and explicitly. Profitability ・ How much cost can be cut by lowering friction coefficient by 0.01? Example : Fuel saving by friction reduction at piston- cylinder wall

12 s No. of cars in use 71×10 6 s No. of gas cars in use 57×10 6 s Gasoline sales 57×10 6 kl s Total gasoline cost $57×10 9 Statistics (Japan, 1998)

13 Fuel Energy Consumption in a Car : EPA Mode 62% : Thermal 6% : Air pumping 3% : Piston-Cylnder 4% : Engine/Others 13% : Others 12% : Wheels %

14 Power Loss Analysis Between Piston and Cylinder Wall Friction coefficient 0.05 for Piston rings 0.03 for Piston skirt Distribution of Mechanical loss 60% for Piston rings 40% for Piston skirt between Piston and Cylinder Wall

15 Possible Friction Reduction ・ 0.01 of Decrease of Friction Coefficient ・ 445×10 3 kL of Fuel or $445×10 6 Cost Saving 30% : coating on rings 20% : barrel-shaped piston skirts →26% Reduction of Average Friction Coefficient

16 Again, What is Expected of TRIBOLOGY and What Can We Do in the Future? ・ Predictability ・ Controllability ・ Profitability

17 Thank You for Your Attention! Tokyo Kagawa


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