Application of the dynamic stiffness method in the vibration analysis of stiffened composite plates

Abstract

Composite laminates are nowadays extensively applied in many engineering disciplines. Free vibration characteristics of such structures are not always easy to predict by using conventional finite element method (FEM). As an alternative, the dynamic stiffness method (DSM) can be applied to predict free vibration characteristics of composite plate assemblies, especially in mid and high frequency ranges. Key feature of the DSM is the dynamic stiffness element (DSE) and its dynamic stiffness matrix, derived from the exact solution of the governing equations of motion in the frequency domain. Consequently, the structural discretization is influenced only by the change in the geometrical and/or material properties of the structure. The number of unknowns is significantly decreased in comparison with the FEM, without losing the accuracy and reliability of the results. In the paper, the DSE based on the higher order shear deformation theory (HSDT) is applied to study free vibration analysis of composite stiffened plates. The numerical analysis has been carried out through an illustrative example in order to check the accuracy of the proposed method. The influence of side-to-thickness ratio on the free vibration characteristics of stiffened plate has been studied numerically. The results are validated using the available analytical data as well as with the FEM solutions.