Free Vibration Behavior of Grid Stiffened Composite Plates with Various Boundary Conditions

The present research aims to investigate the free vibration behavior of composite plates stiffened by stiffeners with various boundary conditions, using numerical and analytical methods. In the analytical approach, smeared stiffness method is employed to superimpose the stiffness contribution of the stiffeners with those of the plate in order to obtain the equivalent stiffness parameters of the whole structure. Using the Ritz method, the governing eigenvalue equations are obtained and solved for evaluating the natural frequencies of vibrations of the stiffened composite plate. After the analytical study, finite element analyses of the stiffened composite plate are also conducted by using commercial finite element software (ABAQUS) that takes into account the exact geometric configuration of the stiffeners and the skin to observe the free vibration behavior corresponded to various boundary conditions. Numerical results confirm the accuracy of the analytical method. Furthermore, some new interesting results are presented and the effects of stiffeners geometry, skin thickness and boundary conditions on the natural frequencies are discussed