Ultrasonic friction reduction in elastomer - Metal contacts and application to pneumatic actuators

Ultrasonic friction reduction is well known in metal-metal contacts. Due to the vibration, the stick phase in the contact phase vanishes and only sliding occurs. As long as the macroscopic relative velocity of the contact partners is much lower than vibration velocity, the necessary force to move the parts tends to (nearly) zero. If the effect also exists in material combinations with a significant difference in stiffness and damping characteristic has not been investigated in the past. This contribution shows the effect for various material combinations, which are typical for sealings in pneumatic actuators. Further, a novel integrated transducer design for a pneumatic actuator is presented. In this design the transducer also acts as moving part within the pneumatic actuator. The design challenges are the two contact areas on the moving part, where the friction reduction and consequently high vibration amplitudes are needed. The first area is fixed on the transducer geometry, the other is moving along the piston. This novel design has been implemented in the laboratory; detailed experimental results are presented in this contribution