A Fundamental Study on Frictional Noise : 1st Report, The generating mechanism of rubbing noise and squeal noise

The generating mechanism of frictional noise in dry friction is experimentally and theoretically studied, when a contact rod clamped at one end is pressed in the radial direction on a rotating disk. The results are obtained as follows: (1) Frictional noise is classified into two categories, rubbing noise and squeal noise. (2) When the coefficient of friction between the rod and the disk is small, the vibrating energy is small. Therefore, the frictional noise is rubbing noise, which is of a low level. (3) When the coefficient of friction grows great as the result of the tip of the rod being worn, the rod vibrates in the lateral direction as in the fundamental mode. Thus the vibrating energy increases and the frictional noise changes to the squeal noise, the sound pressure level of which is higher than the rubbing noise by 20-30 dB. These lateral vibrations seem to be self-excited vibrations caused by the friction.