Comparison of two analytical methods used to calculate sound radiation from radial vibration modes of a thick annular disk

Two analytical solutions for acoustic radiation from the radial structural modes of a thick annular disk with free boundaries are described. The far-field modal sound pressure is calculated first by using the Rayleigh integral formula and then obtained by treating the radiating surfaces as two cylindrical radiators. Modal sound power, radiation efficiency and directivity predictions are confirmed by using a boundary element code. Measured frequency responses also support the propsed theory.