Numerical Research On Dynamic Bucking Of Sphere-cylinder Combined Shell Under Axial Impact Load

The submarines develop rapidly with the ocean development and significant application in military.Sphere-cylinder combined shell is widely used in the practical engineering,especially as the main form of the submarine pressure hull,and often bears the impact load on practical engineering.Therefore,there is important theoretical and practical significance for the research on impact characteristic of the combination shell.The paper adopts the combination shell as the object,while the finite element method is mainly applied to analysis the dynamic performance under the impact load.The main content is as follows:1.With simple bar under impact load as example,the theory of stress wave under the impact load is briefly introduced,including the establishment and solving of basic equation and the phenomenon of elastic and elastic-plastic stress wave.2.The finite element method of structure dynamic buckling is discussed.As a kind of common dynamic algorithm,center difference method is also introduced.With the analysis of the algorithm,it is proved that dynamics problems under impact can be dealt with the finite element program ls-dyna.As the cylindrical thin steel tube for example,the finite element method is used to analyze the structural characteristics under axial impact with numerical ways.3.The dynamic buckling phenomenon of elastic sphere-cylinder combined shell under axial impact load is solved in the numerical research.The structure deformation nodal under different load is observed while the development process of structure form in different time is showed,and the time history curve of each physical variable is given.The displacement,stress,and inertial effect will be analyzed in detail through the process of the impact,while their changes discussed.4.The dynamic buckling phenomenon of elastic-plastic sphere-cylinder combined shell under axial impact load is solved in the numerical research.the buckling process under impact will be analyzed in detail。The influence of different geometric parameters(such as thickness),physical parameters(such as the tangent modulus,yield strength)and condition parameters(such as peak load)on buckling process will be analyzed emphatically.5.In the situation that the rest condition is totally identical,the dynamic buckling process with different material properties will be compared to explore the influence of difference material on buckling process.