A DYNAMIC STIFFNESS TECHNIQUE FOR THE VIBRATION ANALYSIS OF STIFFENED SHELL STRUCTURES

A dynamic stiffness method is presented for the analysis of stiffened shell structures. The method is based on a singly curved orthogonally stiffened shell element which has a constant radius of curvature and which is simply supported along the curved edges. The stiffeners are taken to be smeared over the surface of the element, and Hamilton's principle is used to derive the appropriate modifications which must be made to the shell differential equations and boundary conditions. The resulting differential equations are solved exactly to yield the dynamic stiffness matrix and the loading vector for the element. Any number of elements may be assembled to model the cross-section of a built-up structure such as an aircraft fuselage. A discrete stringer element is also derived which enables the detailed analysis of smaller structural components such as an array of stiffened panels. The method is applied to a range of stiffened circular cylinders, a cylinder with an internal floor, and a five-panel/six-stringer array. © 1992.