Analysis Of Dynamic Characteristics Of Thin Circular Cylindrical Shells

Shell structures have been widely used in so many engineering areas, it is light, high strength and can bear heavy weight, and it is interesting and challengeable to study the dynamic characteristics of shells.In this dissertation, Brief reviews about shell theories, natural characteristics and transient dynamic response and harmonic dynamic response of circular cylindrical shells are given first. The difference classical relationships between stress, strain and displacement using Flugge’s, Donnell’s and Love’s thin shell theories are reviewed, and implemented into the dynamic equilibrium equations by using Hamilton’s Principle.According to Love’s shell theory, the governing equations of thin cylindrical shells are established and the effects of Coriolis acceleration and Centrifugal force are considered. The three sets boundary conditions are considered:simply-simply, clamped-clamped edges. The transfer matrix method and beam functions are presented to study the vibrations of the stationary and rotating cylindrical shells. The relationships between natural frequencies and nodal diameters can be found, and the bifurcations of natural frequencies due to rotation are discussed for rotationally closed shells.The forced vibrations of non-rotating orthotropic circular cylindrical shells are investigated based on the first Love’s approximation theory. The boundaries conditions are considered as simply-simply edges. The conventional modal expansion method is used to develop the analytical solution for the harmonic point load and the impulsive point load in the radial direction. Next, a new approach is developed for solving the general forced vibration response problem of rotating cylindrical shells. The solution in its final form is characterized by generalized coordinates. Then the influence of rotation on the forced vibration is illustrated.Finally, modal testing is used to analyze the natural characteristics of the clamped-free shells, and the modal testing result has been compared with mathematical simulation.