Research On Distorted Scale Model Of Nonlinear Stability Of New Typical Dry Gasholder With Typical Imperfections

The new dry typical gasholder is a large space combined shell structure.The top of the new dry typical gasholder can be regarded as a stiffened spherical shell,and the gasholder body can be regarded as a stiffened cylindrical shell.As a large pressure vessel with a thin-walled shell as the main body,it is very important to ensure the safety of the structure.Large-scale thin-walled cylindrical shells are prone to instability and lead to structural failure.At the same time,the structural system is very sensitive to initial geometrical imperfections.Therefore,it is necessary to perform nonlinear stability analysis on stiffened cylindrical shells.In the prototype stability test,the large-scale stiffened shell is bulky,the construction process is complicated and the manufacturing price is high,so there are many limitations such as high cost,difficulty,and long cycle.Therefore,the stability test results of the scaled model are usually used to predict the stability characteristics of the prototype structure.And,the scale principle formula of the nonlinear stability and the design method of the scale model are particularly important to evaluate the reasonableness and the safety of the new dry typical gasholder.This paper mainly focuses on the stiffened spherical shell and the stiffened cylindrical shell commonly used in the top and the body of the new dry typical gasholder.In-depth and systematic research is carried out on two aspects: the scale principle formula of the nonlinear stability and the design method of the scale model.The main contents include:(1)General similitude requirements and the scaling laws for nonlinear buckling of stiffened orthotropic shallow spherical shells are presented by applying similitude transformation to the total energy of the structural system.In the absence of the experimental data,structural similitude is completed by numerical experiments.Then,the scaling model of the stiffened orthotropic shallow spherical shell is established,and the fully similar and incompletely similar simulation studies of the linear and nonlinear stability of the structure are carried out.The results show that the derived scaling law has good accuracy in predicting the similarity between the linear and nonlinear behavior of distortional scaling models of the stiffened orthotropic shallow spherical shells.(2)Based on the discrete stiffener theory and the energy method,the generalized similarity conditions and the scaling principle formulas for the nonlinear stability of discrete stiffened cylindrical shells with initial geometric imperfections under uniaxial loading are proposed.First,to ensure the correctness of nonlinear stability analysis,the nonlinear stability of cylindrical shells with initial geometric imperfections under uniaxial loading are verified by the nonlinear stability algorithm.Then,an incomplete similarity simulation study of the structural nonlinear stability of ring and string discrete stiffened cylindrical shells under uniaxial loading is carried out.The results show that the derived scaling law has good accuracy in predicting the similarity of the nonlinear stability distortion scaling model for ring and string discrete reinforced cylindrical shells with typical imperfections under uniaxial loading.(3)Based on the discrete stiffener theory and the energy method,the generalized similarity conditions and the scaling principle formulas for the nonlinear stability of discrete stiffened cylindrical shells with initial geometric imperfections under combined loading are proposed.First,to ensure the correctness of nonlinear stability analysis,the nonlinear stability of cylindrical shells with initial geometric imperfections under combined loading are verified by the nonlinear stability algorithm.Then,an incomplete similarity simulation study of the structural nonlinear stability of ring and string discrete stiffened cylindrical shells under combined loading is carried out.The results show that the derived scaling law has good accuracy in predicting the similarity of the nonlinear stability distortion scaling model for ring and string discrete reinforced cylindrical shells with typical imperfections under combined loading.(4)The generalized similarity condition of structural nonlinear stability and the application of the scaling principle formula in the new dry typical gasholder with typical imperfections are explored by using the finite element method.Firstly,based on the structural characteristics and force conditions of the new dry gas cabinet body,a simplified model of the real gas cabinet body-truncated cabinet model is choosen.Then,the simulations of nonlinear stability incomplete similarity of truncated cabinet model under axial pressure,lateral pressure and combined loads are carried out by applying the equations of nonlinear stability incomplete similarity scaling principle of ring and string discrete reinforced cylindrical shell;the accuracy of the equations of nonlinear stability incomplete similarity scaling principle of discrete reinforced cylindrical shell and the design method of distortional scaling model are verified.Finally,by comparing the prediction error of the scaling model based on the discrete reinforcement theory truncated cabinet nonlinear stability with that based on the smeared stiffener theory under axial pressure,lateral pressure and combined loads,it is found that the prediction error of the scaling model based on the discrete reinforcement theory truncated cabinet nonlinear stability is smaller than that based on the smeared stiffener theory.This shows that the discrete stiffener theory has better accuracy for similar prediction of the nonlinear stable distortional scaling model of the new dry typical gasholder with typical imperfections.