Mechanics Analysis Of Buckling And Post Buckling Of Sandwich Shallow Cylindrical Moderately Thick Shallow Shells

The sandwich structure has developed rapidly under the impetus of a large number of new structures and new materials,the mechanical properties are gradually getting people's attention.In particular,the buckling analysis of sandwich structures has become one of the hot spot in the field of solid mechanics and engineering applications.Based on the buckling theory of the thick cylindrical shallow shell,this paper research the buckling of sandwich shallow cylindrical moderately thick shallow shells systematically and deeply which consider sandwich layers of system stiffness,and also research the post-buckling analysis of functionally graded interlayer and homogeneous material of sandwich shallow cylindrical moderately thick shallow shells.the results of research have certain academic value,and also have very important engineering application significance.The main contents of this thesis are as follows:In the first part,using the method of double Fourier series,in the analysis of the four edges simply supported thick laminated cylindrical shallow shell buckling under axial load.Consider the in-plane stiffness of sandwich,and thick laminated cylindrical shallow shell inside and outside the surface and in the sandwich layer for homogeneous materials.Through the thick laminated cylindrical shallow shell displacement mode,according to the isotropic medium thick cylindrical shallow shell theory,the use of thick laminated cylindrical shallow shell geometric equations,constitutive relation,the balance equation,displacement is established in the form of static buckling of thick laminated cylindrical shallow shell control equation.This expression can be degraded as the expression of hard sandwich sandwich plate,show the correctness of the derivation process.And discussed the sandwich layer of elastic modulus and poisson's ratio and thick sandwich cylindrical shallow shell in aspect ratio and the influence of thickness of shallow shell buckling load.Results show that the critical load and the sandwich layer is directly proportional to the modulus of elasticity and poisson's ratio,aspect ratio and thickness of shallow shell is inversely proportional to.In the second part,using the galerkin method,analysis of the simply supported boundary conditions of functionally graded inter-layer in thick cylindrical shallow shell under axial load after buckling analysis.Ignore the in-plane stiffness of sandwich layer and thick laminated cylindrical shallow shell inside and outside surface of homogeneous material,the sandwich layer for functionally graded materials.Based on the nonlinear geometric equation of thick laminated cylindrical,constitutive relation and balance equation,is established on surface in stress function,deflection and two corner for the function of the independent variable gradientin thick cylindrical shallow shell buckling of the nonlinear differential equation.Four edges simply supported by semi analytical method,the boundary conditions in the functionally graded inter-layer thickness post-buckling equilibrium path of cylindrical shallow shell,analyzed the functionally graded inter-layer in thick cylindrical shallow shell thickness,length,radius and core material on the surface and under the surface of elastic modulus ratio on the buckling load.Structure in the functionally graded inter-layer nonlinear critical load of thick cylindrical shallow shell with shallow shell increase with the increase of the displacement,presents the typical nonlinear characteristics.As the thickness of surface layer of shallow shell,shallow shell length and core material on the surface and under surface of the increase of the elastic modulus of functionally graded inter-layer in thick cylindrical shallow shell nonlinear critical load increase.