Analysis on transmission of sound and vibration of underwater double cylindrical shells connected with noncontinuous slab ribs

To analyze the sound and vibration transmission characteristics of double finite cylindrical shells, modal superposition method is adopted to establish the analytical mode, in which interaction induced by water between shells and slab ribs connecting the shells is taken into account. The in-face and out-face motion of slab ribs bring forth the interaction of shells, and the former factor features in the vibration transmission of the double shells below the ring frequency of the shell. The circumferential discrete slab ribs is mathematically described as algebraic sum of some step functions, which is then expanded in sine function series to fit in with the control equation of double shells. The results show that: whether the slab ribs are discrete or continuous as an annular rib, the level of sound radiation of double shell doesn't alter a lot, instead of which, only the peak points move a bit. Keywords: Sound radiation, Step function, Double cylindrical shells