Vibroacoustic Modelling of Submerged Stiffened Cylindrical Shells with Internal Structures under Random Excitations.

The vibroacoustic behavior of a structure excited by a partially space-correlated random pressure field such as turbulent boundary layers (TBL) or internal diffuse fields is of great interest for aeronautical or naval applications. Many works have been carried out for structures such as plates or simple cylinders whereas little attention has been paid on more complex cases. The aim of this paper is to study this problem for a ribbed cylindrical shell coupled to internal structures. The proposed modelling is based on the combination of two methods developed recently by the authors: the wavenumber-point (k,M) reciprocity technique and the Condensed Transfer Function (CTF) method. The first one estimates the sensitivity functions at point M of the system from its vibratory velocity field induced by a point excitation at M. This velocity field is estimated with the second method. The CTF method is a substructuring approach which consists in coupling a semi-analytical model of a submerged cylindrical shell with Finite Element models of axisymmetric (ribs, bulkheads) and non-axisymmetric (floor partitions, engine foundations) internal frames. A numerical example of a submerged stiffened cylindrical shell excited by a TBL will be given and the influence of the internal frames will be discussed.