An Experimental Study on Voltage-Controlled Friction of Alumina/Brass Couples in Zinc Stearate/Water Suspension

Abstract

Dependence of the friction coefficient of Al₂O₃/Cu couples lubricated with a zinc stearate suspension on external voltage has been investigated on a ball-on-disc rotation type and a pin-on-plate reciprocating motion type test device. Both of the ball-on-disc and pin-on-plate test results showed that friction coefficient increased remarkably when a voltage greater than certain critical value was applied, and it decayed to ordinary levels as the voltage was removed.

Active control of friction coefficient of Al₂O₃/Cu rubbing couple was attempted in two demonstrational cases. In the first case, the real friction coefficient was tuned to follow a pre-assigned step-up change in the real-time of rubbing process by adjusting the applied external voltage with a simple feedback control scheme. In the second case, friction coefficient was controlled to yield to a pre-assigned sinusoidal variation with the same control algorithm. Test results have shown that the actual friction coefficient can approach its goal values in both cases within accuracy of 3% if control parameters are proper. Experiments with various control parameters have indicated that improper control parameters lead to slow convergence and even oscillation.

Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in San Francisco, CA October 21–24, 2001

KEY WORDS:

• Friction
• Control
• Ceramics
• Metals
• Suspension

Notes

Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in San Francisco, CA October 21–24, 2001