| In the “13th Five-Year National Science and Technology Innovation Plan”,China proposed to build a new-generation residential deep-sea operation platform,the Deep Sea Space Station.As a deep-sea space station,the circular toroidal shell is an ideal structure for the main structure of the pressure hull.In order to ensure the reliability of its design and manufacture,it is very important to make a correct prediction of buckling characteristics,one main forms of the failure of the circular toroidal shell under uniform external pressure.At the same time,considering the lesser standards of the China Classification Society(CCS)and pressure vessels for the circular toroidal shell under uniform external pressure,it is important to study the buckling characteristics of the circular toroidal shell and find an efficient and accurate buckling load prediction method.It is of great significance to provide the necessary technical support for the safe development of marine exploration work.The research contents and conclusions of this paper are as follows:(1)By comparing the linear buckling analysis with the experimental results,the effects of element type,element density and boundary conditions on the stability analysis of the circular toroidal shell are discussed.A reasonable finite element analysis model is proposed.The error between the theoretical solution,the numerical solution and the experimental value of the critical buckling load is compared,and the numerical solution is consistent with the experimental results,while the theoretical solution calculated by the Jordan formula has a large error.The buckling loads of a circular toroidal shell with different thickness-to-diameter ratios are calculated,which proves that the Jordan formula results are conservative.When t/r≥1/14,it is possible to directly predict the buckling load of the actual condition of a part of the structure based on the numerical calculation results.(2)By comparing the nonlinear buckling analysis with the experimental results,it is proved that for most practical structures,it is necessary to use nonlinear buckling analysis considering nonlinear conditions such as material and large deformation.It is proved that although the thickness variation of the circular toroidal shell cannot be fully reflected in the numerical analysis,the approximate true thickness can be used to approximate the test results to the greatest extent.It is found that under the same conditions of average thickness,a specific parameter variable thickness circular toroidal shell has better resistance to buckling than a single thickness one.(3)The effects of ribs on the buckling characteristics of the circular toroidal shell are studied by comparing linear buckling analysis with test results.Compared to discrete ribs,the critical buckling load of this type of rib stiffened circular toroidal shell is reduced due to the poor lateral stability of the continuous ribs.In the case that the rib itself has not been unstable,the critical buckling load of the ribbed circular toroidal shell increases as the moment of inertia of the rib section increases.The semi-circular ribs with better lateral stability do not significantly increase the critical buckling load of the ribbed circular toroidal shell compared to the rectangular ribs.In general,the rectangular section discrete ribbing method has the best effect on the reinforcement of the circular toroidal shell.(4)The hydrostatic pressure test is carried out on four 304 stainless steel and eight resin samples.Comparing the test results and numerical analysis results of the 304 stainless steel circular toroidal shell,it is proved that the circular toroidal shell is not sensitive to the initial geometric imperfections,and the specific parameter variable thickness circular toroidal shell has better resistance to buckling.Comparing the test results and numerical analysis results of the resin circular toroidal shell,it is proved that the numerical analysis can predict the buckling and post-buckling behavior of the circular toroidal shell. |
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