4 - Finite element analysis of flexural vibration of orthogonally stiffened cylindrical shells with ATILA

Abstract

The vibration and sound radiation of structures, like plates or shells stiffened by frames or ribs, is a problem of interest in the analysis of aircraft and marine structures. If the ribs are uniformly spaced, then the composite structure is spatially periodic. Many authors have proposed solutions for stiffened infinite shells with simple shapes. But, when the shape is more complicated, such as for a submarine or an aircraft, the numerical methods are not appropriate and the finite element method seems justified with finite element characterizing the stiffeners. In this chapter, from the theory of shells with the complicating effects of anisotropy due to the stiffeners, one finite element is presented. After, the presentation of the boundary conditions on the shell, a first validation will be realized on circular cylindrical shells having tranverse stiffeners. The modes of vibration obtained from the new shell element are compared with analytical and experimental results. The second validation concerns an elastic target with a stiffened shell. The comparison is made between the use of the new shell element and a 3D analysis.