Effect of boundary conditions on natural frequencies for rotating composite cylindrical shells with orthogonal stiffeners

The effect of the boundary conditions on the natural frequencies for rotating composite cylindrical shells with the orthogonal stiffeners is investigated using Love's shell theory and the discrete stiffener theory. The frequency equation is derived using the Rayleigh-Ritz procedure based on the energy method. The considered boundary conditions are four sets, namely: (1) clamped-clamped; (2) clamped-simply supported; (3) clamped-sliding; and (4) clamped-free. The beam modal function is used for the axial vibration mode and the trigonometric functions are used for the circumferential vibration mode. The composite shells are stiffened with uniform intervals and the stiffeners have the same material. By comparison with the previously published analytical results for the rotating composite shell without stiffeners and the orthogonally stiffened isotropic cylindrical shells, it is shown that natural frequencies can be determined with adequate precision. (C) 1999 Elsevier Science Ltd and Civil-Comp Ltd. All rights reserved.