The purpose of this paper is to investigate the mechanism of impact noise generation, in order to reduce noise at its source. A fundamental model, the case of a ball striking a clamped circular plate, was studied. In the experiments, the effects of plate thickness and observation distance on sound pressure were observed. In the theoretical analysis, the rotary inertia of the plate, shear deformation, and the air reaction of the radiated sound were considered. The impact force history was assumed to be a triangular pulse, since it was determined by three parameters: the maximum impact force, the impact duration, and the rise time. The time when the maximum sound pressure occurred, the influence of the rise time on the sound pressure level, and the vibrational modes which contributed to the sound were obtained using this approximation.
The purpose of this investigation is to get a fundamental theory for the reduction of impact noise.The sound caused by the impact of a ball on a relatively thin circular plate clamped at its edge was investigated experimentally and theoretically and the theoretical results almost agreed with the experimental results.The impact sound in this paper is due to the forced vibration of the plate. The forced vibration problem was solved with consideration of the damping of the plate and Hertz's contact theory was also introduced to analyze the impact phenomenon.The impact force was calculated by the small increment method and the sound pressure was calculated by assuming that the point sources were distributed all over the plate surface. The influence of both impact duration and maximum impact force on the impact sound were investigated and it was found that the impact sound pressure level depends on the amplitude of the impact force histories and the frequency components of the impact sound pressure depend on the impact duration.
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