The approximation of pressure waveforms of impact sound radiation from clamped circular plates of various thicknesses

Abstract

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.

Impact sound radiated from a viscoelastically supported circular plate.

“…The impact sound of a plate viscoelastically sup portedat its edges is compared with that of a and M. NAKAI:IMPACT SOUND OF VISCOELASTICALLY SUPPORTED PLATES clamped plate. Our findings are as follows: (1) Inserting rubbers is effective to reduce the level of the free vibration sound, when the plate is thin in comparison with its diameter or the level of the free vibration sound is sufficiently higher than that of the initial peak. Thus when a viscoelastic material of suitable elastic stiffness is chosen, it can minimize the maximum value of the impact sound.…”

A Review of Prediction Methods for the Transient Vibration and Sound Radiation of Plates

“…The Hertz contact theory is widely used to analyze this impact force [8]. The collision process is often modeled by a sphere colliding with the plate [9][10][11][12][13][14][15][16][17]. This process is the most typical representation of impact phenomena and the one which has been most extensively investigated, both theoretically and experimentally.…”

“…This is valid where the time taken for the elastic waves to reflect from the lower surface of the plate back to the impact region is much longer than the contact duration. However, if the influence of the plate's thickness needs to be considered, the vibration equation of the plate should also be introduced [15]. Combining this with Hertz's theory, Takahagi and Nakai [15] calculate the impact force histories using both the classical and Mindlin's theories.…”

“…Mackertich and colleagues [19] also point out that the classic plate theory is useful only for frequencies where the ratio of wavelength to plate thickness is higher than eight. Based on these findings, some researchers [11,13,14] derive the transient vibration equation by using the thin-plate theory in which the normal mode analysis method is used to solve the equation in the time domain; while other authors [15,17] use the Timoshenko-Mindlin plate theory to analyze the transient field of the thick plate. The results confirm that the results calculated for the thick plate, using the Timoshenko-Mindlin theory, correspond more closely to the experimental findings than those obtained by the thin-plate theory, especially in the initial peak.…”

The effects of elastic supports on the transient vibroacoustic response of a window caused by sonic booms

“…Apart from studies of the steady state problems, other research has analyzed the transient response of plate-like structures. [5][6][7][8][9][10][11][12] In these studies, Forsyth and Warburton 11 analyzed the transient response of cantilever plates to an impulse force. Craggs 12 investigated the transient responses of clamped, simply supported, and cantilever plates using the transition matrix method.…”