Scattering model of a cylindrical shell with internal axisymmetric frames by using the circumferential admittance approach

Laurent Maxit (1, 2)

1 LVA - Laboratoire Vibrations Acoustique
2 CeLyA - centre Lyonnais d'Acoustique

A numerical model is proposed for predicting the scattering pressure by a fluid-loaded cylindrical shell stiffened by axisymmetric internal frames and impacted by an acoustic plane wave. The proposed developments consist in an extension of the Circumferential Admittance Approach (CAA) [Maxit, et al., J. Acoust. Soc. Am., 128, 137-151 (2010)] to an obliquely incident plane wave excitations. CAA consists in assembling a numerical model of the fluid loaded shell with finite element models of the internal frames. The scattering pressure model deduced from CAA can then take into account: (a), internal frames having a cross section with a complex geometry and thickness variations (like T-shaped stiffeners, bulkheads, hemispherical end caps); (b), variations of the frame spacings; (c), the frame-shell coupling in the three translational directions and the tangential rotation. Comparison with numerical and experimental results of the literature for a periodic stiffened shell shows that the scattering from Bragg, Bloch-Floquet, and Helical waves are correctly predicted. The effects on the backscattering pressure of the axial and tangential coupling forces are highlighted. Finally, an example of non-periodically stiffened shell is presented to highlight the versatility of the proposed approach.

Mots clés: Acoustic scattering Stiffened shells Bloch-Floquet wave Modelling

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]

Laurent Maxit. Scattering model of a cylindrical shell with internal axisymmetric frames by using the circumferential admittance approach. Applied Acoustics, 2014, 80, pp.10-22. ⟨10.1016/j.apacoust.2014.01.002⟩. ⟨hal-00994286⟩