Study On Structural Response And Ultimate Bearing Capacity Of Hull Head Under Slamming Load

The slamming process involves complex analysis techniques such as strong nonlinearity of waves,instantaneous effects,hydroelastic effects,and fluid-solid coupling.It has always been one of the hot topics in the field of marine engineering.The dynamic instability of ship structure under slamming load leads to the decrease or even complete loss of the overall bearing capacity of the ship,which accounts for a large proportion of marine accidents every year.Therefore,in order to ensure the dynamic stability of the ship structure under dynamic loads and avoid the damage of the slamming load to the hull structure,it is necessary to accurately predict the slamming load of the hull when sailing in waves,and carry out the analysis and research on the response and ultimate bearing capacity of the hull head structure under the slamming load.This paper is based on the subject of " Research on XX Failure Mode and Ultimate Bearing Capacity of the Head Structure Based on XX Analysis." Firstly,the design and verification of the fluid-solid coupling numerical model simulation considering the elastic deformation effect of the structure are completed in combination with the water entry slamming test of a typical three-dimensional elastic structure,and the parametric effects of different wave peaks and different plate thicknesses on structural deformation and slamming pressure are studied.Then,the numerical prediction of the slamming load in the bow area of the catamaran sailing in waves is carried out.Based on the spatial and temporal distribution characteristics of the slamming load in the bow of the catamaran,the slamming load characteristics of the rigid body and the catamaran considering the elastic effect are compared.Finally,the dynamic response of bow slamming under different impact load shape parameters is studied.Through the study of the static ultimate bearing capacity of the hull structure and the slamming dynamic response under different impact loads and their corresponding failure modes,a reference method for measuring the ultimate bearing capacity of the hull bow structure under the slamming load is proposed by the dimensionless ratio of the plastic residual deformation in the impact load direction to the ultimate deformation corresponding to the static ultimate bearing capacity.The specific research contents are as follows:(1)The basic theories of finite volume method,VOF model,finite element method and structural rigid response are introduced.The numerical simulation technology of wave based on VOF method and the cooperative coupling theory of STAR-CCM+ and Abaqus are given.On this basis,the numerical model of coupling response of hull structure under wave slamming load is established,including the numerical simulation of regular wave,the characteristic effect of structural wave coupling response and the parametric influence of ship speed and wave parameters.This theory overcomes the defects of structural rigid response and unidirectional coupling under water entry and wave load,and provides theoretical support for the following numerical simulation.(2)In order to reveal the wave slamming phenomenon and load distribution characteristics of the simplified structure,a three-dimensional numerical model of the wedge is established by using the STAR-CCM+ and Abaqus collaborative coupling technology to simulate the vertical water entry process of the wedge,and the numerical model is verified by comparing the slamming pressure and free surface dynamics of the water entry measuring points of the wedge.Based on the validated numerical model,the effects of wave peak,wedge structure plate thickness and wave climbing direction on the water entry impact response characteristics of the wedge are analyzed.(3)The wave slamming of catamaran and the coupled structural response of the bow area are studied.Firstly,the finite element model of the catamaran is established by Patran.Secondly,the slamming scene is determined by the design wave method based on the specification.Combined with the abaqus and STAR-CCM+ joint simulation method,a three-dimensional nonlinear wave slamming load numerical simulation technology is established to predict the hull slamming load of the catamaran during wave navigation,and the spatial and temporal distribution characteristics of the wave slamming load on the hull surface,especially the head structure area,are obtained.Finally,the coupling response of wave slamming and bow structure of catamaran under different boundary conditions is studied.The slamming load characteristics of rigid body and catamaran considering elastic effect are compared,which provides guidance for the design and strength check of local structure of catamaran under wave slamming load.(4)The ultimate bearing capacity of the bow structure of the catamaran under slamming load is taken as the research object.The finite element model of the bow part is established by using the large finite element software Patran.The numerical simulation technology of the ultimate bearing capacity of the bow structure based on the quasi-static method is established by using the nonlinear finite element software abaqus.The static ultimate bearing capacity of the bow structure is studied.The bending moment-rotation curve,static ultimate strength and static ultimate rotation angle of the hull girder under static load are obtained,and the static ultimate bending moment and ultimate rotation angle based on the limit state are obtained.The parametric effects of slamming load duration,slamming impulse and slamming load amplitude on the dynamic response characteristics of bow are studied.A new method for evaluating the slamming dynamic bearing capacity of ship bow structure is proposed by comparing the static ultimate bearing capacity of ship bow with the slamming dynamic response under different impact loads.