Study On Collapse Response Of Ship Structure In Freak Wave

Freak wave’s height is greater than twice of the significant wave height.According to the existing data,many ships have structural collapse accidents due to freak waves with large wave height,resulting in damage to personnel and property,which has attracted the attention of ship mechanics researchers all over the world.According to statistics,the waves that can cause the collapse of ship structures are rare freak waves with large wave height.Therefore,it is necessary to update the wave model and take the nonlinear freak waves as the input wave model for the numerical simulation of ship structure collapse.The structural collapse of ship structure under waves is essentially a nonlinear fluid structure coupling problem.In addition to the inevitable structural nonlinear problems such as plasticity,buckling and fracture,it will also be accompanied by nonlinear loads such as large deformation of ship external surface,deck wetness,liquid surface breaking and slamming,they two are coupled and affect each other.It is necessary to use the nonlinear fluid structure coupling method to study the structural collapse of ship structure under freak wave,and explore the research method suitable for simulating the structural collapse under freak wave,so as to provide reference for the structural design of ocean going ships.The two-way coupling method of CFD(Computational Fluid Dynamics)-nonlinear finite element is used to study the collapse response of ship structures.Firstly,the numerical theoretical model of freak wave is investigated and studied,and the nonlinear Schr?dinger breather solution theory is determined as the model of freak wave.The breather solution theory value,that is,the velocity field distribution of the freak wave,is obtained and input into the STAR-CCM+ numerical pool of the large CFD platform for wave making,so as to realize the numerical freak wave simulation based on STAR-CCM+;Then,the collapse model test of the ship’s hydro elastic-plastic model under the freak wave is carried out to realize the wave making of the freak wave under the laboratory conditions,and the hydro elastic buckling model which can produce the structural collapse under the freak wave in the pool is designed.It is composed of the rigid cabin section at the bow and stern and the buckling hinge structure in the middle.The time-domain buckling angle curve of the test model under the freak wave is measured by the wireless inclinometer sensor;Then,the CFD nonlinear finite element two-way coupling method is used to numerically simulate the hydroelastic buckling model test under the freak wave,establish the numerical pool model based on STAR-CCM+ and the hydrodynamic model of Hydroelastic buckling structure,realize the generation of numerical freak wave and the calculation of wave load of Hydroelastic buckling model,and map the wave pressure to the wet surface of Hydroelastic buckling structure finite element model,The large-scale nonlinear finite element solver ABAQUS is used to calculate the structural large deformation of the hydroelastic buckling model.The two-way collaborative simulation technology based on STAR-CCM+ and ABAQUS is used to solve the large deformation of the hydroelastic buckling model under a series of test conditions.Compared with the test results,the agreement is good,which verifies the effectiveness of the numerical simulation method and the model test structure proposed in this study;Finally,the numerical simulation of the collapse response of 4600 TEU container ship structure is carried out by using the CFD nonlinear finite element two-way coupling method verified by experiments,and the structural collapse mode and response characteristics of container ship under freak wave are studied.The research has reference significance for the collapse response prediction of ship structure under the action of freak wave and the structural design of ocean going ships.