Dynamic Response And Buckling Of Stiffened Cylindrical Shells Subjected To Under-Water Explosion Loadings

On the basis of discrete stiffened model, taking the stiffener section as rectangular, assuming the flow field to be incompressible,predigesting the underwater explosive wave loading reasonably, taking the hydrodynamic impulsive loading into account, the analytical model of the stiffened cylindrical shells is constructed. By way of effective analysis method, the dynamic response and dynamic buckling of stiffened cylindrical shells subjected to underwater explosive loading induced by spherical charges are studied numerically and theoretically in this paper. The aim is to provide some meaningful conclusions for enhancing the strength of the underwater structures. The major work in this paper is as follows:The advances in the research of free vibration and dynamic response and dynamic buckling under impact loading of stiffened plates and shells are reviewed comprehensively at first. The dynamic characteristics of stiffened cylindrical shells subjected to underwater explosive loading are mainly commented.First the process of TNT charge exploding underwater is simulated with the code MSC.DYTRAN, and the dynamic response of the stiffened cylindrical shells subjected to the underwater explosive loading are computed emphatically by the two coupling methods (General coupling and ALE). The results are proved to be correct after comparing with some correlative literatures.Then discrete the stiffened cylindrical shell into shell-beam system by the rigid joint, the equations of structure motion subjected to underwater explosive loading are derived from Hamilton variational principle, considering the shear deformation, rotation interia of the shell and shear deformation, bending deformation and tension deformation of the stiffeners. The partial defferential equations are transformed to ordinary differential equations by Galerkin method and solved numerically by fourth-order Runge-Kutta method. The effects of the hydrodynamic impulsive loading, the static water pressure, the geometrical parameters of the stiffeners, the thickness of the shell,ηj =B j/Hj ratio and the terms of Fourier series on the dynamic response are discussed. Some common experiences are validated. On the basis of aforementioned analysis ,the nonlinear dynamic response of the stiffened cylindrical shell subjected to the underwater explosive loading are investigated, considering the effects of the initial geometric imperfections and the large deformation. Some appreciate conclusions are summarized. The elastic-plastic dynamic response of the stiffened cylindrical shells subjected to underwater explosive loading are studied through increment numerical method. The constitutive relation accord with Mises yield criteria and isotropic hardening increment theory. The effects of stiffeners, the uniform circumferential external pressure and the strain-rate sensitivity of materials on the elastic-plastic dynamic response are discussed.Next the nonlinear dynamic buckling of the stiffened cylindrical shells subjected to combined radial underwater explosive loading and axial fluid-structure impact loading are analyzed. The criterion proposed by Budiansky and Roth is applied to obtain the critical loading. The buckling modes and the critical loadings of the structure subjected to the axial fluid-structure impact loading and the radial underwater explosive loading are studied respectively. Then the relation between the critical loadings on the two directions are emphasized. The effects of the circular stiffeners on the bearing ability against axial impact , the buckling modes and the critical loadings are discussed. On the other hand the elastic-plastic dynamic buckling subjected to the underwater explosive loading are also studied. The B-R criterion and Southwell method are used. The effects of the geometrical parameters, the hardening parameters on the structure critical loadings are examined.