| The new type of dry gas holder is a large space special steel structure.Its body is a large stiffened cylindrical shell,which is mainly subjected to axial pressure and external lateral pressure.As a large pressure vessel with thin-walled shell as the main body,it is very important to ensure the safety of the structure.At the same time,the structural system is very sensitive to initial geometric imperfections,so it is necessary to carry out post-buckling analysis of stiffened cylindrical shells.It is very limited by the test site and economic conditions to carry out the buckling test of large-scale stiffened cylindrical shell prototype structure.Generally,it is necessary to study the stability characteristics of the structure through scale model experiment.In this paper,the longitudinal ring rectangular stiffened cylindrical shell is taken as the research object,and the generalized similarity condition and scale principle formula of the stiffened cylindrical shell are derived based on the dense reinforcement theory and energy method innovatively.On this basis,based on the dimple imperfection function,the static analysis of the stiffened cylindrical shell is carried out by displacement loading,and the dimple imperfection is introduced into the perfect structure by updating the node coordinates of the finite element model The finite element model of stiffened cylindrical shell with dimple imperfection is designed and established;the scale models of post buckling under axial and lateral compression are studied respectively,and the complete similarity and incomplete similarity analysis of nonlinear buckling under axial and lateral compression are carried out.The main contents include:(1)Based on the assumption of close stiffened theory,the longitudinal ring rectangular stiffened cylindrical shell is equivalent to orthotropic cylindrical shell.Based on the total energy of the structure system remains unchanged,the generalized similarity condition and scale principle formula of stiffened cylindrical shell are derived and established.In view of the fact that the geometric scale ratio and material parameters change at the same time,the simplified scale formulas of stiffened cylindrical shells under axial and lateral compression are given.(2)Based on the dimple imperfection function,by updating the node displacement coordinates in the finite element model,the dimple imperfection is introduced into the ideal structure,and then the finite element model of stiffened cylindrical shell with dimple imperfection is established.The correctness of the finite element model and post buckling calculation is verified by the analysis of an example.(3)The complete similarity and incomplete similarity analysis of stiffened cylindrical shells with dimples under axial and lateral compression are carried out respectively.The results show that the post buckling of stiffened cylindrical shells with dimples under axial and lateral compression is completely similar.Combined with the corresponding buckling scale principle formula,the post buckling results of corresponding prototype structures can be accurately predicted;the post buckling results of stiffened cylindrical shells with dimples under axial and lateral compression can be accurately predicted The results show that the post buckling of dimple stiffened cylindrical shells is not completely similar.The results can accurately predict the prototype structure with similar material parameters.When the numerical difference of Poisson’s ratio increases,the prediction error will increase.It shows that the formula of scale principle is accurate.Based on the above research,the generalized similarity condition and scale principle formula of post buckling of longitudinal ring rectangular stiffened cylindrical shell under axial and lateral compression derived by energy method can provide useful reference for model design and experimental verification of axial and lateral compression stability of large stiffened cylindrical shell with local geometric imperfections. |
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