Opening Reinforcement Design And Experimental Investigation Of Cylindrical Shell For Deep-sea Submersible

The submersible is the most important equipment in marine exploration.Pressure hull,as the pressure bearing part of submersible,provides a safe environment for submersible personnel and equipment.Cylindrical shells are widely used in submersibles or submarines with a working depth of less than 800 m because of their ease of processing,high space utilization and low fluid motion resistance.The opening of pressure hulls is essential in practical application.The opening of pressure hulls will destroy the mechanical properties of pressure hulls.Therefore,it is of great significance to study the opening reinforcement of pressure hulls.The research contents and conclusions are as follows:(1)Designing a cylindrical shell with opening reinforced based on CCS Code.Firstly,the working depth of the submersible and the inner diameter of the cylindrical pressure hull are determined.Then,by comparing the commonly used design methods of hole reinforcement,the more widely used and more reliable equal area method is chosen to reinforce the shell wall with hole.Finally,the other dimensions of the shell and the parameters of the wall reinforcement are calculated according to the Code,and the parameters are checked.(2)Comparing the strength and stability of intact cylindrical shells and reinforced cylindrical shells with openings.Firstly,the strength of the key parts of the complete cylindrical shell,the critical instability load of the intercostal shell plate and the whole shell are calculated by theoretical calculation.Then,the numerical models of complete cylindrical shells and coaming-reinforced cylindrical shells are established,and their strength,linear buckling and non-linear buckling are analyzed respectively.Finally,the theoretical calculation results,numerical analysis results and numerical analysis results of the whole cylindrical shell are synthetically analyzed.The results show that the mechanical properties of the whole cylindrical shell are retained in the reinforced cylindrical shell.(3)Rationality of introducing equivalent geometric defects is verified by proportional model test.Firstly,the influence of opening reinforcement parameters on the stability of cylindrical shells with openings is studied.It is concluded that the thickness of the wall has the greatest influence,the height of the wall in the shell takes the second place,and the height of the wall outside the shell has the least influence.Then,the optimal combination is selected and the proportional model is made.The finite element analysis,real defect numerical analysis and hydrostatic pressure test of the model are carried out.Finally,the analysis results are compared.The results show that after obtaining the material parameters,the true profile and thickness parameters of the manufacturing model,the unsteady pressure of the pressure hull can be obtained by numerical analysis.At the same time,the method of introducing equivalent geometric defects is effective and feasible.(4)Comparing the mechanical properties of cylindrical shells with different reinforcement types.Firstly,the holed cylindrical shells strengthened by the combination of coaming and inserted thick plate are designed by equal area method,and the numerical analysis of the composite strengthened cylindrical shells is carried out.The results of the analysis are compared with those of the numerical analysis under the type of coaming strengthening.The results show that the ultimate strength of the composite strengthened cylindrical shells is greater.Then,the scale model of the composite reinforced cylindrical shell is made,and the real defect numerical analysis and hydrostatic pressure test are carried out.Finally,the experimental results of two types of reinforcement are compared,and the results show that the mechanical properties of cylindrical shells with combined reinforcement are better.