Some Problems Of Vibration Analysis Of Stiffened Plane And Shell Structures

This thesis is focused on the study of vibration behaviors of stiffened shell and plane structure. By referring to an experimental data of a stiffened plane, models in the same conditions have been built to study the numerical errors while changed the types of elements or counts of nodes. According to the results, it is better to choose them with attributes of various models. For optimizing the stiffened plane models with beam-element stiffeners, the effect between rotational freedom of shell elements and motional freedom of beam elements has been considered.The models with different parameters have been investigated for discovering the further effects of stiffeners. There are two distinguished results while fixing the width or thickness of stiffener but changing the lengths of other edges. However, it shows the same tendency while keeping a constant ratio of width over thickness. Moreover, the counts or positions of stiffeners on a plane change, the natural frequencies change accordingly.In the study of a cylindrical shell, a relative precise model has been built by analyzing the effect of element types, freedoms on nodes and mesh densities. Furthermore, by considering the effect of nonlinear geometry, the cylindrical shell model, in different internal pressures, accelerations and rotational speeds, have been analyzed.