Research On Buckling Characteristics Of Stainless Steel Cylindrical Shell With Imperfections

The cylindrical shell structure is widely used in the industrial field.In the field of offshore engineering equipment,the cylindrical shell is often used as the leg of the offshore platform and mainly bears axial pressure.In this paper,the failure behavior of medium-height 304 stainless steel cylindrical shells with length imperfections and thickness imperfections under axial compression is studied.It will be instructive for future research and design of cylindrical shells with length and thickness imperfections under axial pressure.First of all,the nonlinear and linear buckling of cylindrical shells are theoretically studied.Before the beginning of nonlinear buckling theory,modern methods of nonlinear calculation are introduced.After deducing the linear and nonlinear theoretical formulas,the international design specifications for the axial compression of cylindrical shells are introduced.Secondly,the 304 stainless steel cylindrical shells are tested and analyzed.First,the paper obtains the mechanical properties of 304 stainless steel,obtains the end imperfections data,obtains the appearance parameters of the cylindrical shell by the three-dimensional scanner,and obtains the critical load and instability mode of the 304 stainless steel cylindrical shell by the axial compression test.Based on the axial compression test,combined with the classical linear buckling theory and CAE analysis results,the correctness of the finite element model and method of the cylindrical shell is verified,and the selection of the calculation method for the cylindrical shell under axial compression is determined.The study shows that for the cylindrical shell of the paper,the load that caused the yield of the cylindrical shell is closer to the test load value than the axially-compressed elastic critical buckling load,and the American AISC are more in line with the test results.Thirdly,the buckling analysis of 304 stainless steel cylindrical shells with length imperfections is conducted.An axial compression test is performed on a cylindrical shell with a relatively small diameter and thickness.The end of the cylindrical shell is unconstrained and has a random length difference.Combining the classical linear buckling theory and numerical analysis results,the effect of the length imperfections at this time on the critical load and buckling characteristics of the 304 stainless steel cylindrical shell is discussed.The results show that the critical load of a cylindrical shell with plastic buckling is very different from that of a cylindrical shell with elastic buckling.The end length imperfections will cause irregular deformation during axial compression and weaken the initial axial bearing capacity of the cylindrical shell,which is reflected in the reduction of the critical load value,but the effect of this imperfections on the critical load value of the cylindrical shell in this paper can still be considered slight.Finally,the buckling study of thickness imperfections is carried out on the 304 stainless steel cylindrical shell.The effect of imperfections on the critical load when the shapes of the imperfections are the same,but the locations are different is studied.The impact of the critical load of the cylindrical shell with the same locations and areas and with different shapes of the imperfections is studied.The influence of the rotation angle and aspect ratio of the square imperfections at the same position on the critical load is studied.The results show that the critical load is not always positively related to the cross-sectional area of the imperfections.The weakening effect of circular imperfections on the buckling critical value of cylindrical shells is slightly greater than that of square imperfections.The effect of imperfections on the critical load decreases as the thickness of the cylindrical shell increases.