Dynamic Buckling Of Cylindrical Shells Under Coupling Loads

At present people for buckling study focuses on the structure under a single load,but most of the structures are under coupling loads in engineering,and their dynamic performances differ from the ones under a single load,so it is necessary to study them.Impact load is an important type of the load,and the structure under impact buckling is far more complicated than static buckling.In addition,cylindrical shells are widely used in engineering, so people have been concerned about their dynamic buckling under coupling loads.To solve the difficulty of dynamic buckling under coupling loads,it is very important to establish good mathematical model and to choose better solution.When the Hamiltonian system is introduced into the problem of dynamic buckling,dynamic buckling of elastic cylindrical shells in Hamiltonian system is established under axial and torsion impact.In other words,the problem uses dual variables in Symplectic space instead of variables in traditional Euclidean space.Thereby the variable separation method and the Symplectic eigenfunction expansion method give out an exact solution space.In the Hamiltonian system,higher-order partial differential equation and numerical method are solved by increasing unknown quantity and reducing order.The Hamiltonian system combined with the numerical method gives full play to the advantages of duality system and computer.Then many engineering problems are solved.The critical buckling loads and buckling modes are solved.The critical parameters are affected by propagation and reflection of stress wave under coupling loads.Different supports, geometric conditions and physical conditions also have effect on the critical buckling loads and buckling modes of cylindrical shells.The numerical results show that torsional load has influence on axial impact of cylindrical shell,so buckling process has become more complex. They influence each other and determine the dynamic buckling of cylindrical shells. Cylindrical shells in fixed,simple and free support have different buckling loads and modes under coupling loads.Diameter-thick ratio and poisson's ratio also affect critical loads. Actually the cylindrical shells are limited in length,and the speeds of compressed stress wave and torsional stress wave are unequal under coupling loads.As a result,the features of propagation and reflection of stress wave make buckling performance with special form.