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

According to Made in China 2025,the marine engineering equipment will be developed rapidly,and deep-sea submersible is important marine engineering equipment for ocean exploration and deep-sea scientific research.The pressurized shell is an important part of submersibles and plays a decisive role.Openings in the pressurized shell are essential,these openings are used for personnel access,observation and parts installation.For a pressurized complete spherical shell,the opening will weaken its mechanical characteristics,so whether the reinforced spherical shell retains the original mechanical characteristics is particularly meaningful.The current works are as follows:(1)Based on the underwater working conditions of 7000 m,the reinforcement design of the pressurized spherical shell with an opening was employed.The influence of mesh division type,cell type and cell density on the mechanical characteristics of the pressurized spherical shell with an opening was investigated.The results showed that the solid and shell meshes had little effect on the results of numerical analysis for medium thick shell.The difference of the mechanical characteristics between the complete spherical shell and the spherical shell with an opening reinforced by the wall were compared.The difference of the strength between the complete spherical shell and the spherical shell with an opening was 2.5%,indicating that the wall compensates for the reduced strength caused by the opening.The difference in nonlinear buckling critical load was 0.28%,indicating that the stability of both is very close.The spherical shell with an opening reinforced by wall retains the mechanical characteristics of the complete spherical shell.(2)The effects of the wall thickness,height of the upper part of the wall,and height of the lower part of the wall on the buckling of a spherical shell were demonstrated numerically according to the buckling load.The optimal parameters were obtained by orthogonal experiment.The results show that the initial pressure increases nearly linearly with an increase in the wall thickness and height of the lower part of the wall,but after this initial increase,the load plateaus and does not increase with further increases.The height of the upper part of the wall has little effect on the critical load of the spherical pressure shell with an opening.In order to verify the rationality of the optimization results and equivalent geometric imperfections,two proportional models were manufactured and tested.(3)In order to obtain the effect of different reinforcement structures on the mechanical characteristics of the pressurized spherical shell with an opening,the two types of reinforcement methods of the wall reinforcement and the combination reinforcement of wall and thick plate are respectively adopted for the pressurized spherical shell.The differences between the two methods of reinforcement were compared by numerical analysis.In order to verify the rationality of the numerical analysis results,the proportion resin models of two pressurized spherical shells with reinforced structures were fabricated using mature 3D printing technology.The paper contains a comparison between theoretical predictions,numerical analysis results and experimental data for two reinforced spherical shells.The results show that the combination reinforced structure makes the spherical shell with an opening have higher strength and better stability,in which the strength is increased by 1.67%,the stability is improved by 10.1%,The difference between the spherical shell with an opening reinforced by wall test value and the numerical critical buckling load is 4.5%,but the difference between the test value of spherical shell with an opening with the combined reinforcement structure and the critical load value of the numerical analysis is 2%.