Effect of Rotating Speed and Stiffeners on Natural Frequency of Composite Shell

The effect of rotating speed and stiffeners on vibrations for composite rotors is investigated using Sander's shell theory. The frequency equation is derived implementing the Rayleigh-Ritz procedure based on energy method. The effects of initial hoop tension, centrifugal and Coriolis forces due to the rotation are considered to derive governing equation. The displacement functions satisfying the both ends simply supported boundary conditions are assumed to be trigonometric expressions. By using simple shell theory like as Sander's shell theory the amount of equations and time expenditure are considerably reduced and provides feasible analysis, solution and design especially for composite materials optimization. UD composite materials are used for stiffeners. The effects of these stiffeners are evaluated by an averaging method. Some of stiffeners shapes are considered to optimize the ratio of natural frequency to weight.