Finite Element Free Vibration Analysis of Laminated Composite Stiffened Shell

Abstract

Free vibration analysis of composite stiffened shell panels has been carried out for the first time. As there is no published literature available on the problem, the finite element technique has been applied using two elements, namely the nine-noded Lagrangian element and the heterosis element, for obtaining new results. An improved version of the stiffener modelling is presented here. In this modelling, stiffeners can be placed anywhere inside the element and it need not pass through the nodal lines. Moreover, both elements have the capacity of accommodating curved boundaries and incorporating transverse shear deformation. Results for stiffened composite cylindrical shells and doubly curved shells with different boundary conditions and various laminae orientations have been presented for both concentric and eccentric stiffeners. Parametric studies considering different variables have also been carried out.