Buckling Analysis Of Thin Cylindrical Shells With Random Initial Imperfections

Due to its superior bearing capacity and simple manufacturing process,thin cylindrical shells are widely used in aerospace,military missiles,liquid tank storage and other modern engineering.When the main operating condition of thin cylindrical shells is axial pressure,its failure mode is buckling instability.A large number of practices and research have showed that the buckling load of a cylindrical thin shell is extremely sensitive to the imperfections generated during its manufacturing,installation and service and other links,and the uncertainty of these imperfections and the non-linearity in the instability analysis of thin-walled structures have led to the quantitative research on the sensitivity of buckling loads of thin cylindrical shells very challenging,and has been receiving widespread attention in academic and engineering.A novel random field approach is proposed to model the initial geometrical imperfections of thin cylindrical shell structures,based on which a stochastic analysis method for buckling analysis of thin cylindrical shells with initial geometrical imperfections is proposed.Firstly,it is pointed out that the existing method to characterize the initial geometrical imperfections of cylindrical thin shells as 2D Gaussian random field would lead to the initial geometrical imperfections inconsistent with the actual situation,such as the cylinder circumference significantly increased or decreased geometrical imperfections.Secondly,a random field modeling method considering the constant perimeter constraint is proposed to eliminate random geometrical imperfections which do not correspond to the reality.Finally,based on the initial imperfections random field model,a non-intrusive polynomial chaos expansion method is proposed for the stochastic buckling analysis of thin cylindrical shells,and the probability distribution results of critical buckling loads are given.Numerical results show that the initial geometrical imperfections modeling method based on random field theory can effectively describe the influence the geometrical imperfections on the bearing capacity of structures,while the proposed constrained random field modeling method can reduce the dispersion of analysis results caused by random field model.