Research On Stability Of Pressure Sphere-cylinder Combined Shell Based On Stiffness Reduction

With the proposed goal of strengthening the ocean powers,it is the first task of the Chinese navy to vigorously develop its naval equipment.Build a submarine with greater depth of dive and better performance is a basic indicator for the development of a strong navy.Pressure shell structure is the main form of its submarine design,which is to solve the shell to resist the load of the strength of the external structure and the stability of the proposed better design specifications.In order to reduce the dependence on the experimental data during the design process,it is necessary to derive the relevant theoretical derivation of the stability of the pressure hull and to give the specific expressions of the critical loads that can be compared and applied.The direct calculation of the stability of the shell,the study of the stiffness of the expression on the stability and the discussion of the stability of the structure under common defects formula is of theoretical and practical significance.The main content of this article:(1)Deriving the stability of cylindrical shell structure,the definite expression of the total potential energy of nonlinear term that clearly affects the structural stability.The analytical expressions of two kinds of instability modes are solved by applying the stability criterion and the correctness is verified by comparison with the specification,the formula is analyzed to explore the effect of stiffness changes on the structural stability,the influence of shell and rib stiffness on bearing capacity of column shell is analyzed.(2)According to the symmetry of the spherical shell,derived from the total potential energy that affects its stability,the final determinant matrix is given in the critical load calculation.Take a ball over the heart of the slab beam instability range analysis,derive the corresponding critical pressure expression,the linear formula of the range of instability under a certain parameter is obtained.Applying numerical software to fit out the critical load instability expression of spherical shell in a certain parameter range and comparing with the specification.(3)According to the ball shell combination shell structure of the intersection of location induction characteristics,establish a generalized displacement function expression that ignores the continuous corners.Under the new displacement function,the total potential energy of composite shell structure is deduced and give the final matrix form,the overall destabilization mode is analyzed,derive the critical pressure expression for each form.The numerical fitting method is used to give the general fitting formula of instability and compared with the finite element results.(4)The effects of two common initial defects on the structural stability are discussed,the stability critical load expression of shell instability under linear and nonlinear conditions is derived,determine the defect parameters that affect the stability,the instability expressions are compared and analyzed.