Friction Sound Generated in Rubbing of a Ball on Unidirectional Asperity Surface

Micro impacts between asperities on a contact interface are the sources of sound generated in rubbing contact, particularity at low load. Since the asperities are highly random, the quality and the quantity of the generated sound are generally related to roughness parameters such as Ra. In this study, a contact surface that has uniform periodic asperities was used to investigate the characteristic of the sound produced by asperity impact. The results show that the peak frequency of generated sound corresponds to the structural principle frequency of the asperity, i.e. the peak frequency of the sound corresponds to the peak frequencies of the normal and tangential acceleration of the structure. It is revealed that the peak frequency of generated sound in the rubbing is related to one of the principle frequencies of the asperity excited by the impact during sliding. These results suggest that control of the friction sound, particularly in low contact load, could be done by controlling the shape and the dimension of the asperities.