Study On The Dynamic Response Of Hull Structure Based On The Hydro-elasto Plasticity Approach

It is a dynamic nonlinear process when large ships encounter extreme sea conditions and the whole structure collapses,and the strong nonlinear coupling effect between structural deformation and wave load needs to be considered when analyzing its structural response.Therefore,this paper adopts a theoretical method of hyro-elasto plasticity to accurately describe the process of change of carrying capacity of super-large ships in the event of damage caused by extreme sea conditions,and to evaluate the residual value and safety requirements of ships.In this paper,the motion balance equation is established for the hyro-elasto plasticity model,and the solution of the parameters in the equation is drawn.In view of the coupling equation between structure and load,the analytical solution of structural collapse under the influence of extreme load is obtained,and then the influence of various parameters on the severity of the collapse is discussed.And for a double hull bulk carrier under the action of various target extreme waves,the dynamic response of the structure and the ultimate strength after its collapse are numerically calculated and expounded.Finally,the hyro-elasto plasticity test design and research of the tank hull girder are carried out.The main research work of this paper is as follows:1)By establishing a hyro-elasto plasticity model of hull beam,the model simplifies the hull beam collapse model into a nonlinear spring system in the middle of the two rigid body models to simulate the "plastic hinge" formed by the collapse of hull beam structure.The coupling equation between the structural model and the mathematical model of the extreme wave load is obtained,the analysis and solution of the structural collapse is obtained.Based on this,the influence of various parameters on the structural collapse is studied and discussed.The structural motion balance equation is solved by Newmark-β method.2)The first-order reliability method is used to obtain the wave height function under extreme sea conditions.In this paper,the reliability index is taken as 4,and the timedomain nonlinear method based on the ordinary strip method is used to evaluate the external wave load.3)In this paper,a double-hull bulk carrier is selected as a calculation case.First,the finite element method is used to calculate the ultimate strength of the sag and hog of the mid-hull structure to obtain the relationship between bending moment and curvature.The curve relationship is used as an input file to represent the nonlinear bending moment-curvature relationship of the spring system in the model,and is used to study the dynamic response process of the hull under extreme waves.4)The response of double-hulled bulk carrier under extreme waves is analyzed by hyroelasto plasticity approach,and the dynamic response of hull beams in different period and at different wave heights is mainly studied in this paper.5)By weakening the girder structure of a ship,a slat beam structure was designed,and the hyro-elasto plasticity was experimentally studied.