TAILORING THE DYNAMIC CHARACTERISTICS OF COMPOSITE PANELS USING FIBERORIENTATION

One of the advantages of composite structures is the ability to tailor their characteristics by using different lamination schemes. The pres ent paper studies the effects of various lamination schemes on the lin ear and nonlinear natural frequencies of symmetrically laminated compo site panels. The nonlinear equations account for geometric nonlinearit ies and allow finite displacements and rotations. Numerical studies of a graphite/epoxy panel show that the dominant nonlinearities are cubi c and that both the linear and nonlinear natural frequencies of the pa nel can be altered significantly by changing the orientation of the fi ber in the various plies. However, the nonlinear behavior of the panel remains of the hardening type. It is also shown that the strongest no nlinearities are associated with the lowest linear natural frequency w hereas the weakest nonlinearities are associated with the largest line ar natural frequency.