Hybrid ray-mode parametrization of acoustic scattering from submerged internally loaded thin cylindrical elastic shells: Reformulation of angular harmonic resonant mode data.

Abstract

Angular harmonic resonant-mode expansions have recently been applied to determine the two-dimensional scattering of a plane sound wave incident transversely on a fluid-immersed thin elastic cylindrical shell with a variety of axially invariant internal loadings [Y. P. Guo, submitted to J. Acoust. Soc. Am.]. The scattered field, especially in the mid- and high-frequency ranges, reveals important new features that are due to the internal loading and that appear to be closely tied to traveling waves, with localized induced excitations arising from the vicinity of the lines of attachment of the internal loads. To show these more directly in terms of waves, the problem is reparametrized in terms of the hybrid ray-mode algorithm developed previously for empty source-excited cylindrical shells [L. B. Felsen, J. M. Ho, and I. T. Lu, J. Acoust. Soc. Am.], but augmented now by on-surface equivalent forces induced by the loads. This observable-based parametrization (OBP) is shown to reconstruct the angular harmonics solution with remarkable accuracy, with efficient versatility accommodating loadings of various kinds, and with cogent insight into the relevant physical wave processes. It is therefore suggestive that OBP can be adapted adiabatically to structures that depart from the idealized infinite cylindrical shell model. [Work supported by ONR.]