tribology , its possibility and impossibility yoshitsugu kimura kagawa university
Post on 16-Dec-2015
213 Views
Preview:
TRANSCRIPT
TRIBOLOGY , Its Possibility and Impossibility
Yoshitsugu Kimura KAGAWA UNIVERSITY
・ Heavy industry to IT-related Industry
・ Restructuring in Industry
Recent Changesin Social ConditionsAround TRIBOLOGY
→ Micro-, Nano-scale Tribology
→ Decrease in the Number of Tribologists
What is Expected of TRIBOLOGY and What Can We Doin the Future?
・ Predictability
・ Controllability
・ Profitability
Predictability -Importance of accurate prediction
・ An earthquake M7.0 in greater Tokyo area would cause economic losses of 41×1012 JPYen.
・ Economic losses due to stopping production for 1 day in the area would amount to 0.4×1012 JPYen.
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
Controllability-Changesin the requirement for Tribology
・ Reduction of friction alone
・ Prevention of surface damage
→ Maintaining friction in certain ranges
→ Maintaining wear rates in certain ranges??
Control of Friction-Control of normal load or friction coefficient
Passive control
Active control
・ Selecting Lubricants・ Mechanical Design・ Materials
・ Using active feedback elements or ……
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
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
-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
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
Statistics (Japan, 1998)
Fuel Energy Consumptionin a Car : EPA Mode
62% : Thermal6% : Air pumping
3% : Piston-Cylnder4% : Engine/Others
13% : Others12% :Wheels
100
80
60
40
20
0
%
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
•0.042 between Piston and Cylinder Wall
Possible Friction Reduction
・ 0.01 of Decrease of Friction Coefficient・ 445×103kL of Fuel or $445×106 Cost Saving
30% : coating on rings20% : barrel-shaped piston skirts
→26% Reduction of Average Friction Coefficient
Again,What is Expected of TRIBOLOGY and What Can We Do in the Future?
・ Predictability
・ Controllability
・ Profitability
Thank Youfor Your Attention!
Tokyo
Kagawa
top related