Influence of stiffeners and internal structures on the vibroacoustic behavior of submerged cylindrical shells under random excitations

Abstract

The vibroacoustic behavior of structures excited by random pressure fields such as turbulent boundary layers or diffuse sound fields is of great interest for industrial applications. Many works have been carried out for periodically stiffened plates. In particular, the influence of Bloch-Floquet waves on the panel radiation has been highlighted. However, few studies have investigated more complex structures under random excitations. The present work studies the influence of internal structures on the vibro-acoustic behavior of submerged cylindrical shells. The geometric complexity is successively increased by including periodic, non-periodic stiffeners and various internal frames. The numerical prediction is based on the combination of two methods developed by the authors. The first one is the wavenumber-point (k,M) reciprocity technique. This method estimates the response of the system at point M from the shell velocity in the wavenumber space under a point excitation at M. The velocity field is estimated with the second method, called the Condensed Transfer Function method. It is a substructuring approach which couples a semi-analytical model of a submerged cylindrical shell with Finite Element models of axisymmetric and non-axisymmetric frames. Numerical results are analyzed to evaluate the influence of the stiffeners and the internal structures on the shell radiation.