Effect of Plane-Symmetric Mass Loading on the Response of Ring-Stiffened Cylindrical Shells

An analytical study of the in vacuo vibrations of a simply supported, mass-loaded thin cylindrical shell that is reinforced by equally spaced ring stiffeners is presented. Four masses are attached to each stiffening ring in a plane-symmetric fashion. The rotatory inertia of the masses is taken into account, but similar effects for the shell and ring stiffeners are neglected. Lagrange's equations are used to derive the dynamic equations of the shell structure and the Jacobi iteration method is employed to find the natural frequencies and corresponding mode shapes. Results are given for various values and angular position of the masses. When the value of the masses is allowed to become zero, the results for the ring-stiffened shell are in close agreement with those of previous investigators. Modal analysis is used to obtain the response of the structure to two different types of excitation: (1) a band of uniform internal pressure applied as a pulse in time, (2) a pressure wave that strikes the shell transversely. Numerical results are not presented for these two cases. [The investigation was supported by the U. S. Office of Naval Research.]