Application of the geometrical theory of diffraction for predicting farfield radiation patterns from a vibrating rectangular boxlike structure

Abstract

This paper extends the author's previous paper (presented at the 94th meeting of ASA) on the prediction of farfield sound radiation from a vibrating rectangular boxlike structure resting on the ground from surface acceleration measurements. The lowest‐order approximation of the Green's function which was used earlier can describe farfield radiation only for certain ideal points. An improved approximation to the Green's function (with Neumann boundary conditions) can be fabricated to predict the entire far field radiation pattern from the corresponding Helmholtz integral equation solution for the same problem based on techniques related to the geometrical theory of diffraction. The resulting approximate Green's function takes into account the direct waves and the diffracted waves with the assumption that the sound diffracted by more than one edge of the box makes a negligible contribution to the farfield. The diffracted waves are derived from the uniformly valid asymptotic expression for diffraction of poi...