Research On Ultimate Bearing Capacity Evaluation Technology Of Deep Sea Titanium Alloy Structure

The 21st century is the ocean century.There are abundant resources in the ocean,but the current development and utilization level is not high.The development of ocean resources will provide the material premise and basic conditions for the sustainable development road,and provide huge material support for solving the resource shortage.Therefore,the deep-sea exploration technology plays an important role in the economic development and the promotion of the comprehensive national strength of our country.Manned submersible is an important tool for ocean exploration.It can bring people to the deep sea to investigate the underwater world directly.Its core technology is the design and construction of pressure hull.The ultimate bearing capacity of pressure shell determines the depth of submergence,so it is very important to study the ultimate bearing capacity of pressure shell.In this paper,based on the new titanium alloy material,the deep sea pressure shell is designed.The ultimate bearing capacity of the three kinds of pressure shell is calculated respectively with the intact pressure shell,the open hole pressure shell and the cracked pressure shell as the research object.The main contents of this paper include:(1)The mechanical properties of the new titanium alloy were obtained by tensile test at room temperature.Based on the existing pressure shell forms at home and abroad,combined with the mechanical properties of new titanium alloy materials,a pressure shell suitable for the whole sea depth is designed.(2)Based on the nonlinear finite element method,the ultimate bearing capacity of "deep sea 6500" test model is calculated and compared with the test results to verify the correctness of the method.The method is applied to the calculation of the design shell,and the calculation results are compared with the theoretical results.(3)Based on the new titanium alloy material,the ultimate bearing capacity of pressure spherical shell with single opening is analyzed.Two kinds of opening strengthening methods are used,i.e.traditional wall strengthening and inclined transition strengthening.The influence of wall thickness and height change on the ultimate bearing capacity is analyzed.According to the conclusion of single hole reinforcement,the multi hole design of pressure shell is carried out and its ultimate bearing capacity is calculated.(4)The influence of crack on the ultimate bearing capacity of pressure shell is studied.A single crack is introduced into the multi hole pressure spherical shell,and the change rule of ultimate bearing capacity with the change of crack length,depth and position is analyzed.A multi crack model is established to calculate the ultimate bearing capacity of the spherical shell under the influence of multiple cracks.