A semi-analytical method of free vibration of fluid loaded ring-stiffened stepped conical shell

The motion differential equation of fluid loaded ring-stiffened stepped conical shell is derived by using Flugge classical thin shell theory and equivalent method of ring stiffeners, in which force and moment of a ring stiffener is apportioned in the spacing. In the analysis, the conical shell is divided into many narrow cylindrical strips, the fluid loading of which are available, to consider fluid loading of conical shell approximately. The semi-analytical solution in terms of power series to the equation is then obtained. The free vibration frequencies of a ring-stiffened stepped conical shell in air and in water are respectively solved using the proposed method. The results are compared with the ones obtained from the finite element software ANSYS and they are well agreed.