Structural Optimization Design Of Stiffened Cylindrical Shells With Imperfection Sensitivity

The stiffened cylindrical shell is a kind of thin shell structure which is widely used in aerospace and naval ships with superior mechanical properties.It is of great significance to obtain the mechanical properties of the stiffened cylindrical shell quickly and accurately by effective means.Because the initial imperfections are common in thin shell structures and will lead to a significant reduction in structural performance,imperfection sensitivity analysis is needed.In the structural lightweight engineering,in addition to providing weight loss scheme by developing new configuration with better mechanical properties,the optimal design can be obtained by structural optimization of fixed configuration.This paper mainly carries out the following research work:(1)Based on ABAQUS mechanical analysis software,the finite element mesh division is carried out by using suitable elements,and the appropriate density degree of finite element mesh is determined.By using nonlinear explicit post-buckling analysis method,the post-buckling behavior and collapse load of the traditional cylindrical shell are analyzed.(2)In combination with the eigenmode-shape imperfection analysis method,the eigenmode-shape imperfection is introduced into the perfect structure to obtain its imperfection structure.By changing the amplitude of the eigenmode-shape,the imperfection sensitivity curve of the traditional stiffened cylindrical shell is obtained,and the evaluation index of the structure's resistance to imperfection is achieved.(3)Two new structural schemes for non-uniformly stiffened cylindrical shell are proposed.The mechanical properties of these two non-uniform stiffened cylindrical shells are studied.It is demonstrated that the non-uniform cylindrical shell structure has higher load-carrying capacity and better performance index of resisting geometric imperfections than the traditional stiffened cylindrical shell structure.(4)Combined with the theory of optimization design for engineering structure,the optimization method based on the surrogate model is used to optimization design of the stiffened cylindrical shell.In the process of optimization design,new optimization frameworks with low imperfection sensitivity is proposed,and the practicability of the optimization framework and the applicability of the structure in engineering are tested by the illustrative examples.