A Method for Estimating Ultimate Bearing Capacity of Titanium Alloy Submersible Pressure Spherical Shell

Abstract

The invention discloses an estimation method of ultimate bearing capacity of a pressure spherical shell of a titanium alloy submersible. The estimation method comprises the following steps: step 1: setting relevant parameters of the spherical shell, wherein the intermediate diameter of the spherical shell is r, the different thickness values are t, and the different yield strengths are sigma y; step 2: studying an influence rule of the yield strength of a material on the bearing capacity of the spherical shell; defining the influence of the yield strength on the ultimate bearing capacity of the spherical shell as a plasticity attenuation factor kp and making a solution; step 3: obtaining a perfect spherical shell linear critical buckling load Pnon:pnon=kppm t; step 4: studying an influence rule of initial geometric imperfections on the bearing capacity of the spherical shell; step 5: concluding an estimation formula of the ultimate bearing capacity Preal of the spherical shell: preal=kpkimppm t; step 6: according to relevant parameter values of an actual shell, searching related data, substituting into the related formula, and finally calculating the required ultimate bearing capacity Preal of the spherical shell.

Description

technical field [0001] The invention relates to a method for estimating the ultimate bearing capacity of a pressure-resistant spherical shell of a titanium alloy submersible. Background technique [0002] As an important part and buoyancy unit of the submersible, the pressure hull plays a role in ensuring the normal operation of internal equipment and the health and safety of personnel during the diving process. Its weight accounts for 1 / 4-1 / 2 of the total weight of the submersible. Most of the existing pressure hulls are spherical structures, and the accurate prediction of their ultimate bearing capacity has an important impact on the safety and economic performance of submersibles. [0003] The Code for Classification and Construction of Diving Systems and Submersibles (CCS2013) provides a prediction method for the ultimate bearing capacity of the relevant spherical shell. First, the numerical calculation prediction method, through the simulation calculation of finite ele...

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Problems solved by technology

[0006] After years of research and summarization, finite element numerical calculations can predict the bearing capacity of spherical shells more accurately, but various model parameters need to be set during software calculations, and parameter deviations have a great impact on the results; and there is a lack of systematic research on the mechanism of shell instability and identification

[0007] At the same time, although the calculation formula provided by the classification society can accurately predict the bearing capacity of the titanium alloy spherical shell under specific circumstances, it does not take into account the instability mechanism of the pressure-resistant structure. The formula only involves the tensile strength of the material, not the to other relevant parameters of the material such as yield strength E, elastic modulus μ and yield strength σ y , while the buckling behavior of spherical shells is often closely related to the yield strength

Therefore, the prediction method of the ultimate bearing capacity of the spherical shell lacks a more systematic and widely used theoretical formula prediction method

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