Loading Method Load Adjustment Method In Direct Calculation Of Whole Hull Structural Strength

The research of the hull strength is the science about the safety of the hull structure.In the analysis of the hull strength FEM,in addition to the corrected three-dimensional finite element modeling,the correct loading method also need to be taken into account.Moreover,all the load of the hull finite element model need to meet the strength evaluation requirements.During the assessment of hull strength,the hull loads mainly include light weight,seawater buoyance,wave load and cargo pressure.The load is based on the hull structure,loading conditions,navigation conditions and so on.The process to calculate the ship load according to loading conditions and navigation conditions is very complicated.After the accurate finite element modeling of the whole ship structure,a simplified method of hull strength assessment based on nodal force is proposed in this paper.This method is an extension of the traditional beam theory to assess the strength of the hull structure.Based on this method,nodal forces at strong frames are used to simulate the distribution of bending moment,shearing force and torsion.Through assessment of 4 typical cases,distributions of bending moment,shearing force and torsion along the whole ship are consistent with the target value.The hull design loads include the hydrostatic and wave loading parts.When the load is applied according to the actual loading condition of the hull and external hydrodynamic pressure,the moments,shearing force and torque distributions of the loads on the finite element modal along the length of the ship are different from those of the design requirements.And at this time all the load can not constitute a quasi-static equilibrium force system.Therefore,it is necessary to adjust the load of the whole ship finite element model.Comparing the result of the bending moment and shearing force,the method of load adjustment is reasonable.