Vibroacoustic Response of an Immersed Stiffened Multilayered Shell Excited by a Plane Wave

The modelling of the vibroacoustic response of a periodically rib-stiffened cylindrical multilayered shell is of great interest in numerous industrial applications, including submarine acoustics. An approach is proposed in this paper to couple an immersed multilayered shell model with models of the axisymmetric stiffeners. The multilayered shell may be modeled either with transfer matrix method (TMM) or with direct global method (DGM). Both methods are spectral: displacements and stresses are obtained in the wavenumber domain before reconstructing the solution in the physical domain. This allows us representing different types of layers: isotropic, orthotropic, fluid, etc. The stiffeners are coupled to the multilayered shell at the internal radius of the latter. They are introduced in the formulation by dynamic circumferential admittances which are estimated by classic finite element methods. To illustrate the method we'll present different results as much for validation as for comparison with the unstiffened shell. The configuration retained for the steel shell is the one used in "R. Liétard, D. Décultot, and G. Maze, Acoustic scattering from a finite cylindrical shell with evenly spaced stiffeners: Experimental investigation". Various coatings may be added on top of the shell to study their influence on the antenna performances.