FREE-VIBRATIONS OF LAMINATED RECTANGULAR-PLATES ANALYZED BY HIGHER-ORDER INDIVIDUAL-LAYER THEORY

A higher order plate theory is used in each individual layer to determine the natural frequencies and the relative stress and deflection distributions through the thickness of simply supported rectangular plates. This theory approximates the in-plane and normal displacements by third and second order functions of the thickness co-ordinate, respectively. The theory satisfies the displacement compatibility and stress equilibrium conditions along the interfaces between adjacent layers. Numerical results are calculated for the cases of isotropic and orthotropic homogeneous plates and for symmetric and non-symmetric cross-ply laminates. The present theory predicts more modes of free vibration than other approximate theories. Also, the relative stress and deflection distributions obtained by the present higher order theory are in very good agreement with results by three-dimensional elasticity theory. © 1991.