FREE-VIBRATION OF ECCENTRICALLY STIFFENED LAMINATED PLATES

The free vibration characteristics of laminated plates with discrete s tiffeners are analyzed by the finite element method. The analysis take s into consideration transverse shear deformation effects and rotary i nertias in the plate and stiffeners. The stiffeners are modeled as lam inated beams and are placed along plate nodal lines. A C degrees stiff ened plate element is developed using a nine noded isoparametric plate element and a three noded isoparametric beam element. Natural frequen cies and mode shapes of eccentrically-stiffened laminated plates are p resented to demonstrate the efficiency of the methodology. The influen ces of stiffeners such as depth, number, location and ply orientation on the natural frequencies are examined.