Modeling the dynamics of a compliant piano action mechanism impacting an elastic stiff string

摘要

A realistic model of the piano hammer-string interaction must treat the action mechanism and stringas a single system. In this paper an elastic stiff string model is integrated with a dynamic model ofa compliant action mechanism with flexible hammer shank. Action components represented asrotating bodies interact through felt-lined interfaces for which a specialized contact model withhysteretic damping and tangential friction was developed. The motion of the hammer during stringcontact is governed by the dynamics of the action mechanism, thereby providing a moresophisticated hammer-string interaction than a simple transverse impact hammer model with fixedcontact location. Simulations have been used to compare mechanism response for impact on theelastic string as compared to a rigid stop. Hammer head scuffing along the string and time in contactwere predicted to increase, while hammer shank vibration amplitude and peak contact force weredecreased. Introducing hammer-string friction decreases the duration of contact and reduces theextent of scuffing. Finally, significant differences in hammer and string motion were predicted fora highly flexible hammer shank. Initial contact time and location, length of contact period and peakforce, hammer vibration amplitude, scuffing extent, and string spectral content were allinfluenced.