The Estimation and Measurement of the Sound Power Radiated from a Circular Plate With a Solid Shaft Subjected to an Axial Load

Abstract

The aim is to establish a method for accurately estimating gear noises radiated by the flexural vibration of gear blanks. The basic theory from which is derived the frequency characteristics of radiated sound power is presented. First, the basic theory for estimating radiated and sound power is derived from the definition of loss factor given by Ungar and Kerwin and is confirmed to apply at all frequencies. Second, a thick circular plate with a solid shaft is chosen as a simple model of gear blanks. The natural modes of flexural vibration of the circular plate have been theoretically analyzed in the companion paper [1]; the rigid body modes of vibration of the circular plate are theoretically analyzed in this paper. These analyses produce formulae for deriving the frequency characteristics of three important factors for estimation: the total loss factor, driving point mobility and radiation loss factor of the circular plate. To examine the estimation formula and the associated formulae, experimental data is obtained by impulsively exciting the circular plate in the axial direction, and then measuring the intensity of the radiated sound power. The three important factors for estimating this power (the total loss factor, the driving point mobility and the radiation loss factor of the circular plate) are calculated from the theoretical formulae, and the sound power is then estimated by substituting the measured excitation force into the estimation formula. The estimated radiated sound power agrees well with the measured values both in the low and high frequency ranges where the rigid body modes and the natural modes of flexural vibration exist, respectively.