Free vibration of annular and circular asymmetric composite laminates

Free vibration analysis is carried out to study the vibration characteristics of undamaged annular and circular asymmetric composite plates having completely free edges. The procedure is applicable to plates having asymmetry due to either hybridization or lay-up. The plates are considered to be thin and to undergo small deflections satisfying Kirchhoff's hypothesis. The analysis includes bending-stretching coupling and rotatory inertia effects. The Rayleigh-Ritz energy approach is employed here to obtain the approximate natural frequencies and the associated mode shapes. A complete power series is used as admissible functions for in-plane and out-of-plane displacements. The procedure had been applied to isotropic and symmetrically laminated plates and the results were shown to agree well with other analytical and experimental results in the literature. In this paper, the effects of the size of the plate, number of ply groups, fiber orientation and hybridization on the natural frequencies of asymmetrically laminated annular and circular plates are documented in tabular form, and the mode shapes have been identified.