VIBRATIONS OF PARTIALLY FILLED CYLINDRICAL TANKS WITH RING-STIFFENERSAND FLEXIBLE BOTTOM

The dynamics of a tank partially filled with a liquid having a free su rface is investigated. In the analysis, the effect of free surface wav es is taken into account, so that both bulging and sloshing modes are studied. The structure is completely flexible, and is composed of a ve rtically standing circular cylindrical shell, with ring-stiffeners, an d a flexible bottom that consists of a circular plate generally restin g on an elastic Winkler foundation. The plate edge is joined to the sh ell by coupling rotational springs distributed around the edge. The in teraction between the plate and the shell via the fluid is included. A pplication to the particular cases of (i) a flexible shell with a rigi d bottom and (ii) a flexible bottom plate with a rigid cylinder are al so presented, as well as a comparison with approximate theories. Ring- stiffeners on the shell are also considered in order to investigate th eir influence on the modal behaviour of the tank. Solution of this pro blem is achieved via the method of artificial springs within the frame work of the Rayleigh-Ritz theory, while considering strong fluid-struc ture interaction. (C) 1998 Academic Press Limited.