Friction-induced vibration — with and without external disturbance

The dynamics of friction-induced vibration resulting from a velocity-dependent friction characteristic is studied theoretically and experimentally. The frictional system is further studied in the presence of an external dynamic force. The amplitude of quasi-harmonic vibration is shown to increase with sliding velocity until oscillation ceases at some upper velocity boundary depending on the friction characteristic. The vibration, which can exist at high sliding velocities, may influence the operation of automatic transmissions, brakes and clutches. Introduction of strong damping to the system can reduce or eliminate the induced-vibration. Similar results could be achieved by modifying the friction-velocity characteristic of the fluid and materials at the interface. An external excitation in the transverse direction, with properly chosen frequency and force ratios, can also reduce the amplitude of the friction-induced vibration. The theoretical and experimental results are in good agreement.