Acoustic Radiation from Double Composite Cylindrical Shells with Cyclic Rectangular Rib-Plates: Creeping Waves and Asymptotic Analyses

Acoustic radiation from double composite laminated cylindrical shells with cyclic rectangular rib-plates is analytically investigated by using the Sommerfeld-Watson transform. High-frequency acoustic model of double composite cylindrical shells with rectangular rib-plates is established in terms of creeping waves, geometrical acoustic waves and sound pressure asymptotic integrals. One kind of bending wave boundary layers for the shear deformable rectangular rib-plate is shown. Each set of creeping wave poles for the composite cylindrical shells with rectangular rib-plates is uniformly distributed by the cyclic period. This characteristic still holds for the cyclic structures with the smallest period. Creeping wave poles of the stiffened composite cylindrical shells appear in the entire complex circumferential wavenumber plane. The asymptotic integrals with Airy function are proposed to fast calculate acoustic pressure in the shadow and penumbra regions without making use of creeping wave poles.