Research On Buckling Of Titanium Alloy Pressure Shell Considering Impact Depression

In the 21 st century where ocean development continues to accelerate,deep-sea submersibles have been widely used in many fields such as marine resource exploration,scientific research,and military operations.The submersible needs to withstand a large amount of hydrostatic pressure when submerged on the seabed.The pressure shell is particularly important in various components of the submersible.It can not only help the submersible to resist external static water loads,but also provide more internal space for the submersible.When the submersible is sailing,it may collide with reefs,icebergs,other submersibles,etc.The collision will cause damage,deformation and buckling of the bow structure of the submersible.Based on the summary of the theory of pressure shell collision and structural buckling,this paper uses the finite element software ANSYS/LS-DYNA to study the buckling of the titanium alloy pressure shell considering the collision depression.The main research work is as follows:(1)Understand the research background and significance of titanium alloy pressure shell buckling,grasp the research status of pressure shell,the current research status of pressure structure collision and the current research status of shell buckling.(2)Introduce the modeling method,characteristics and analysis process of the finite element software ANSYS/LS-DYNA,and solve the problems that need attention in the collision simulation(fluid handling,contact and friction problems during collision).The fluid in the collision process is treated by the attached water quality method,and the contact-collision interface is treated by the penalty function method.(3)The static buckling analysis was carried out on the cylindrical rib cylindrical pressure shell and the spherical pressure shell,respectively,and the results of the finite element analysis were compared with the calculation results of the national military standard,the calculation results of the standard test fitting formula,and the calculation results of the correction formula.Compared with the calculation result of the national military standard,the calculation result of the empirical formula considering the influence of the rib is closer to the calculation result of the finite element software simulation.(4)The impact model of the titanium alloy pressure shell is constructed by finite element software,and the dynamic response of the titanium alloy pressure shell under collision is analyzed from the angles of stress/strain,collision force and energy transfer.(5)Numerical simulation is used to analyze the impact depression of titanium alloy pressure shell,and the influence of spherical coronal depression radius,depression depth and depression position on the critical load of cylindrical shell buckling is analyzed using ANSYS buckling analysis module.