Reinforcement Design And Experimental Study Of Deep-sea Pressurized Toroidal Shell With Openings

The deep-sea submersible is an important marine engineering equipment for deep blue exploration of ocean.Pressure shell is the main structure of deep-sea submersible,which ensures the safety of the staff and the stable operation of the instruments and equipment.Traditional spherical shells,cylindrical shells,and conical pressure-resistant structures are relatively well studied,while toroidal pressure-resistant shell has a good hydrodynamic shape,which can overcome the shortcomings of traditional cylindrical shells and is an indispensable pressure-resistant shell structure for deep-sea submersibles.For any submersible,the entrance and exit of the staff,the installation of the instrument and the existence of the observation window are all essential,and openings will have an impact on the performance of the pressure shells.Therefore,the study of the mechanical properties of the opening toroidal shells in this paper is particularly meaningful.The main contents are as follows:(1)Based on the working conditions of the water depth of 800 m,the model of toroidal shell segment,equivalent cylindrical shell,the model of opening toroidal shell segment and equivalent opening cylindrical shell were established,and then based on the mechanical characteristics analysis method of the equivalent model,theoretical calculation and finite element analysis are used to analyze the strength and stability of the toroidal shell section and opening toroidal shell section.The results show that the numerical analysis method is more accurate than the theoretical analysis method in terms of strength and stability,and the strength and stability of the section of opening toroidal shell and the equivalent opening cylindrical shell decrease with the increase of the length of the cabin.When the length of the model cabin is the same,the stability performance of the toroidal shell section and the opening toroidal shell are better than their equivalent cylindrical shells and equivalent opening cylindrical shells.(2)Experimental and numerical methods were used to study the influence of opening parameters on the buckling characteristics of opening toroidal shells.Based on the BP neural network algorithm of particle swarm optimization(PSO),a prediction model was established to predict the buckling performance of opening toroidal shells.The research results show that the nonlinear buckling numerical analysis results(GMINA)of geometric materials with defects are in good agreement with the experimental results.The stability of the toroidal shell with openings decreases with the increase of the opening size.When the opening shape is circular and the number of openings is odd,the stability is better.The BP neural network based on particle swarm optimization(PSO)has higher accuracy than the traditional BP neural network algorithm,and the analysis results of the established predictive model are in good agreement with the numerical simulation results.(3)The geometric parameters of the stiffened toroidal shell with openings are optimized,the Taguchi test is designed to analyze the influence of the geometric parameters on the performance of the toroidal shell with openings,and the comprehensive influence degree of the geometric parameters of the toroidal shell structure.The best combination of buckling performance parameters is obtained.In order to obtain the influence of different strengthening methods on the mechanical properties of the opening toroidal shells,the opening toroidal shells with surrounding wall reinforcement,combined reinforcement of surrounding walls and embedded thick plates,and combined reinforcement of surrounding walls and ribs were studied,and the method of numerical analysis is used to compare the differences of the three strengthening methods.The results show that the wall thickness t0 and the wall inner height h1 have a greater influence on the stability of the opening toroidal shell,and the wall thickness t0 has the largest contribution rate;among the three reinforcement methods,the combined reinforcement of the surrounding wall and the embedded thick plate and the combined reinforcement of the surrounding wall and the ribs are better than those of the surrounding wall reinforcement method.Compared with the surrounding wall reinforcement method,the stability has increased by 18.9% and 7.9%,respectively,and the opening toroidal shell is better reinforced.