Large Amplitude Vibration of Polymer Composite Stiffened Laminates by the Finite Element Method

Abstract

Large amplitude free flexural vibration analyses of composite stiffened plates have been carried out using a C nine noded Lagrangian element. The element, capable of incorporating curved boundaries, is based on the first order shear deformation theory. The large deformation effect of the stiffened plated structures has been taken care of by the dynamic version of von Karman's field equations. The resulting nonlinear equations have been solved by the direct iteration technique using linear mode shapes as the starting vectors. The stiffeners have been modeled with the same shape functions as that of plate element enforcing compatibility without introduction of additional unknowns. A large number of problems of isotropic and composite bare and stiffened plates have been analyzed to validate the formulation and some new results have been put forward for future reference.