EFFECT OF COUPLING BETWEEN INPLANE STRAINS AND TWIST DUE TO ANISOTROPY ON VIBRATION OF COMPOSITE SHELLS

Circular cylindrical and circular conical composite shells (angle woun d) are analysed for their free vibration characteristics using thin (L ove's first approximation shell theory without thickness shear and rot atory inertia) and moderately thick shell theory with shear deformatio n and rotatory inertia. The semi-analytical finite element method is u sed for the solution. Shells with thin shell theory are solved using a two-noded axisymmetric finite element with 16 degrees of freedom per element. Moderately thick shells are solved using a higher order semi- analytical finite element with three nodes and 30 degrees of freedom p er element. The circumferential variation is represented in terms of a double Fourier series in order to incorporate the effect of coupling due to anisotropic properties. Comparison of frequencies of shells usi ng thin and thick shell theories is made to study the effect of transv erse shear and rotatory inertia for various values of average thicknes s to small end radius ratio. A parametric study is made to provide ins ight into the influence of various geometric and material properties o f composite shells.