The sound generated by a transverse impact of a ball on a circular plate.

Abstract

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.

Acoustic signals of rotating drums generated based on DEM simulations

“…As acoustic pressure is often measured in experiments [16], a parameter  is adopted to link displacement in Eq.…”

“…The parameters in Eq. (3), including pressure term , frequency and , were calibrated based on a pendulum impact experiment conducted by Takahagi et al [16]. In the experiment, a steel ball with diameter 12.7 mm collided with a steel plate at the velocity of 1.2 m/s, and the sound signals were collected by a microphone near the surface of the plate.…”

Estimation of the Noise Generated by the Random Impacts on a Thin Plate

“…Fujita らは Herz の接触理論 (Johnson, 1982)もとに 2 つの振動子の衝突による振動現象を定式化し，衝撃力の時間 波形を推定した (Fujita and Hattori, 1980)．また Takahagi らは Herz の理論に基づく衝撃力を適用して円板と球の衝 突音の推定を行い，衝突速度と音圧最大値の関係を示した (Takahagi et al, 1980)…”