Wear Reduction Through Piezoelectrically-Assisted Ultrasonic Lubrication

Ultrasonic vibration has been proven effective in reducing dynamic friction when superimposed onto the macroscopic relative velocity between two surfaces. This phenomenon is often referred to as ultrasonic lubrication. Piezoelectric materials can be employed to generate ultrasonic vibration. Typically, solid or fluid lubricants are employed to mitigate wear. However, in applications such as aerospace systems, which operate in particularly harsh environments, traditional lubrication methods are not always applicable. This paper investigates the relationship between friction force reduction and wear reduction in ultrasonically lubricated surfaces. A pin-on-disc tribometer is modified through the addition of a piezoelectric transducer which vibrates the contact between pin and disc. A piezo-actuator is installed to generate 22 kHz vibration in the direction perpendicular to the disc. Three different linear speeds are employed by changing rotation speeds of the disc and running time. Friction and wear metrics such as volume loss, surface roughness, friction forces and stick-slip effects are compared before and after application of ultrasonic vibration. Relationships between linear speed and friction reduction, stick-slip reduction, and wear reduction are analyzed.