Research Of Vibration Characteristics For Shells Of Revolution And Coupled Structures Subjected To Arbitrary Boundary Conditions

The shells of revolution and coupled structures have been widely used in various engineering fields.It is of great importance both in practice and theoretically to investigate the structural vibration of such shells.The vibration characteristics of such shells are strongly affected by the boundary conditions,so it is of first importance to solve the boundary condition problem.In the actual engineering,the structures are usually subjected to complex boundary conditions,while the traditional solution are mostly restricted the shells with classical supports or some specific boundary conditions.As a result,according to the modeling of the revolve shells and coupled structures subjected to arbitrary boundary conditions,specific research work of the dissertation is presented as follows:Firstly,the basic theory of Spectro-Geometric Method(SGM)is introduced in detail.And then the admissible displacement function of revolve shells is expressed using the present method and a vibration analysis model of revolve shells(cylindrical,conical and spherical shells)with arbitrary boundary conditions is established.The artificial spring technique is adopted along each edge of the shells to simulate various boundary conditions by changing the stiffness constants of restraining springs.All the unknown coefficients of the displacement field functions are treated equally and independently as the generalized coordinates and solved directly by using the Rayleigh-Ritz procedure.On this basis,the vibration characteristics of the revolve shells with different boundary conditions and structural parameters are studied.A vibration analysis model of the coupled conical/spherical-cylindrical shells subjected to arbitrary boundary conditions is developed.The Spectro-Geometric Method is used to construct the substructures’admissible displacement function.The elastic coupler is generally described by translational and rotational springs along the coupling common edge,which is utilized to ensure the continuity conditions.Different coupling conditions can be readily by changing the coupling elastic parameters of the corresponding springs.Ultimately,the unknown series expansion coefficients for the displacement functions of the coupled shells are obtained by the Rayleigh-Ritz procedure.Then,comparisons with previously published results and finite element analyses are implemented to demonstrate the presented approach and unified model.A vibration analysis model of the coupled conical-cylindrical-spherical shells subjected to arbitrary boundary conditions is built using the Spectro-Geometric Method and Rayleigh-Ritz procedure.Then,the convergence and accuracy of the present formulation are checked by a considerable number of numerical examples whose results are compared to those achievable with other methods in the literature.On the above basis,some new results for the coupled shells with various boundary conditions and geometrical parameters are obtained for the first time,which may serve as benchmark solutions for future researches.At last,the effects of the corresponding parameters on vibration characteristics of the couple shells are also studied.A vibration analysis model of the coupled conical-cylindrical-spherical shells with immediate line supports subjected to arbitrary boundary conditions is constructed.The artificial spring technique is adopted at the position of the immediate line supports.Various conditions and styles of immediate line supports are obtained by changing the spring stiffnesses.Ultimately,comparison with finite element analyses is carried out to validate the constructed model.The effects of the position and number of the immediate line supports on vibration characteristics of the coupled shells are also studied.