Measurements of sliding friction forces under ultrasonic oscillations: Out-of-plane oscillations

In the present work, the magnitude of friction force was predicted to be reduced by out-of-plane oscillation applied to contact surface based on `cold-welding model.´ Angular acceleration of the disk that rotates by a weight connected to the pulley was measured while out-of-plane oscillation is applied to the specimen contacting the surface of the disk using BLT (Bolt-clamped Langevin Transducer). The friction force was calculated from the measured angular acceleration. As a result, the magnitude of friction force shows decreasing tendency when the amplitude of the ultrasonic out-of-plane oscillation increases. It implies that out-of-plane oscillation also induces the reduction of the friction force.