Research On Deformation Mechanisms Of Ship Structural Components Based On Typical Ship Collision And Grounding Scenarios

As the fastest growing economy in the world,the total number of ships keeps increasing and sea lanes are getting congested,there is an increasing probability that ships may experience collision and grounding accidents during its using process.Ship collision and grounding accidents have become the leading cause of ship hull damage,casualties environmental pollution and economic loss.Therefore,in order to study the ship collision and grounding performance,reveal the damage deformation mechanism,it is of great significance to do research on the ship structure design based on accidents.Generally,there are three kinds of methods to analyze structural responses in ship collision and grounding actions,as follows: experimental method,nonlinear finite element method and simplified analytical method.Among all the methods,full scale tests are rarely used because the cost is huge and testing technology is limited,as a consequence,model tests are often carried out.Nonlinear finite element method is widely used by scholars at home and abroad because this method can obtain ship structural damage deformation,contact force and energy absorption during collision and grounding accidents.But it is important to note that reasonable and reliable material inputs is the essential to obtain the accurate simulation results from finite element method.The simplified analytical method is a method based on plastic flow theory,which can seize the main deformation mode of structure.The simplified analytical method can be a reference to the emergency plan for accidents and preliminary structural design for ship crashworthiness.Sponsored by national natural science foundation projects,this paper designs and carries out the quasi-static impact test and related numerical simulations to analysis damage characteristics of typical hull structure through analysis and determine collision and grounding scenario of ship structural components.According to the structural damage deformation process obtained from tests and simulations,related mechanical models are established to study the deformation mechanisms of typical ship structural components during ship collision and grounding accidents by theoretical calculation method.Moreover,the structure-reef-fluid coupling model is built,and the grounding performance of a 74,500 DWT tanker structures has been analyzed through simulation calculation.The main works of this paper are as follows:(1)The overview of development trend,research contents and approach of ship collision and grounding are presented.Moreover,the research significance and main contents of this paper are proposed.(2)The basic principle,fundamental formula and calculation procedure of simplified analytical methods are summarized.Then emphatically introduces the common damage deformation mode of ship structural components and the application of simplified analytical methods.Moreover,the material nonlinearity inputs problems of numerical simulation are discussed.The work can provide basis for theoretical calculation method and finite element method.(3)The grillage structures of ship is selected as the research objects,and the quasi-static test and related numerical simulations are conducted to analyze the structural response of plate and stiffened plate punched by flat edge indenter and spherical indenter.According to the features of structural damage deformation process found in the test and simulation analysis,the damage deformation mechanism of structures has been studied and the related analytical formulae are obtained based on the plastic mechanics theory.Finally,the new analytic method is verified and perfected based on the test results.(4)The web girders of hull structure is selected as the research object,including three various forms(unstiffened,transversal stiffened,longitudinal stiffened)and various parameters(the location of stiffener).The quasi-static tests and related numerical simulations are conducted to analyze the structural response of web girders subjected to in-plane load.Then,a new deformation model for unstiffened web girders and a new deformation mode for longitudinal web girders subjected to in-plane load are proposed in accordance with the features of structural damage deformation process found in the test and simulation analysis.Based on the new model,the analytical formulae for energy absorption and impact force are obtained in the light of the plastic mechanics theory.Finally,the new analytic method is verified and perfected based on test results.(5)A 74,500 DWT tanker is selected as the research object,and on the basis of structure-reef-fluid coupling technology,the process of ship grounding is calculated with the nonlinear finite element analysis software ABAQUS.The grounding performance of bottom structure has been assessed through damage deformation,grounding force and energy absorption during accidents.