FINITE-ELEMENT FREE-VIBRATION ANALYSIS OF ECCENTRICALLY STIFFENED COMPOSITE PLATES

Composite stiffened plates have been studied for free vibration by the finite element method in this paper. An isoparametric quadratic plate bending element has been employed for the relevant analysis. In the present formulation, stiffeners can be placed anywhere within the plate element and they need not necessarily follow nodal lines. In addition, isoparametric elements have advantages of accommodating curved boundaries and incorporating transverse shear deformation. Eccentrically stiffened laminates considered for the analysis have different shapes - such as rectangular, parallelogrammic, and annular sector. They have varied stiffener arrangements, cross-sectional properties and included angle. Results of natural frequencies obtained have been compared with those available. Parametric studies have also been carried out.