Estimation and Measurement of the Sound Power Radiated from a Circular Plate with a Solid Shaft and a Solid Cylinder.

Abstract

The overall aim of this research is to establish an effective method for accurately estimating the airborne noise power radiating from the gear blank of aircraft gears.For this purpose, the estimation theory of sound power radiated from a circular plate with a solid shaft and a solid cylinder, which is a simple model of the gear blank of an aircraft gear, has been described.The forced vibration of the circular plate with a solid shaft and a solid cylinder was solved by assuming that the displacement of forced vibration is equal to the linear sum of the eigenfunctions of the displacements of the circular part and the cylinder part.Using the obtained result, the equations for calculating the frequency spectra of three important parameters-the radiation loss factor, driving point mobility, and total loss factor of the circular plate with a solid shaft and a solid cylinder, were derived.Calculating the frequency responses of the three parameters and measuring the spectrum of the excitation force, the sound power, when the circular plate was subjected to the axial and three-dimensionally excitations, were estimated, and compared with the measured frequency responses of sound radiation power obtained by means of the sound intensity method.The estimated freqyency spectra of sound radiation power coincided with the measured values.The derived estimation theory and the associated formulae are valid, consequently.