Comparison of the in-plane natural frequencies of symmetric cross-ply laminated beams based on the Bernoulli-Euler and Timoshenko beam theories

The in-plane free vibration problem of symmetric cross-ply laminated beams is studied based on the transfer matrix method, Distributed parameter model is used in the mathematical formulation. The rotary inertia, the shear and extensional deformation effects, are considered for the Timoshenko's beam analysis. These effects are neglected in the Bel Bernouli-Euler analysis. T he exact overall dynamic transfer matrix of the beam is obtained by making use of the numerical algorithm available in the literature. In older to obt ain detailed knowledge about the effects of the rotary inertia, shear and a xial deformations on rite first six non-dimensional frequencies, the result s of Timoshenko and Bernouli-Euler theories are compared with each other fo r length-to-thickness ratios from ranging 3 to 20. Fixed-fixed, fixed-simpl e, and fixed-free boundary conditions are considered for three values of th e thickness-to-width ratios of a rectangular section (2; 1, 0.5).