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TRIBOLOGY, Its Possibility and Impossibility. Yoshitsugu Kimura KAGAWA UNIVERSITY. → Micro-, Nano-scale Tribology. → Decrease in the Number of Tribologists. Recent Changes in Social Conditions Around TRIBOLOGY. ・ Heavy industry to IT-related Industry.
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TRIBOLOGY, Its Possibility and Impossibility Yoshitsugu Kimura KAGAWA UNIVERSITY
→ Micro-, Nano-scale Tribology → Decrease in the Number of Tribologists Recent Changesin Social ConditionsAround TRIBOLOGY ・Heavy industry to IT-related Industry ・Restructuring in Industry
What is Expected of TRIBOLOGY and What Can We Do in the Future? ・Predictability ・Controllability ・Profitability
Predictability -Importance of accurate prediction ・An earthquake M7.0 in greater Tokyo area would cause economic losses of 41×1012JPYen. ・Economic losses due to stopping production for 1 day in the area would amount to 0.4×1012JPYen.
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
Factors Impairing Accuracy of Prediction During Boundary/Dry Sliding ・Form and dimensional errors ・Surface irregularities ・Surface contamination ・Material contamination ・Changes in these with operation
→ Maintaining friction in certain ranges • → Maintaining wear rates • in certain ranges?? Controllability -Changes in the requirement for Tribology ・Reduction of friction alone ・Prevention of surface damage
Control of Friction -Control of normal load or friction coefficient Passive control ・Selecting Lubricants ・Mechanical Design ・Materials Active control ・Using active feedback elements or ……
→ Control of friction in hydro- • dynamic lubrication Possibility of Active Control With Liquid Crystal Lubricant By applying electric field …… ・Change in apparent viscosity ・Change in friction in boundary lubrication
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
Profitability -Tribologists should show profitability of tribology, quantitatively and explicitly. ・How much cost can be cut by lowering friction coefficient by 0.01? Example : Fuel saving by friction reduction at piston-cylinder wall
Statistics (Japan, 1998) • No. of cars in use 71×106 • No. of gas cars in use 57×106 • Gasoline sales 57×106 kl • Total gasoline cost $57×109
Fuel Energy Consumption in a Car: EPAMode % 62%:Thermal 100 6%:Air pumping 80 3%:Piston-Cylnder 4%:Engine/Others 60 13%:Others 40 12%: Wheels 20 0
Power Loss Analysis Between Piston and Cylinder Wall • Friction coefficient • 0.05 for Piston rings • 0.03 for Piston skirt • 0.042 between Piston and • Cylinder Wall • Distribution of Mechanical loss • 60% for Piston rings • 40% for Piston skirt
Possible Friction Reduction 30%:coating on rings 20%:barrel-shaped piston skirts →26% Reduction of Average Friction Coefficient ・0.01 of Decrease of Friction Coefficient ・445×103kL of Fuel or $445×106 Cost Saving
Again, What is Expected of TRIBOLOGY and What Can We Do in the Future? ・Predictability ・Controllability ・Profitability
Thank You for Your Attention! Tokyo Kagawa