Study On Residual Strength Of Typical Hull Components With Crack Considering Non-uniform Corrosion Effect

Ships and offshore structures are subjected to alternating loads for a long time,the fatigue cracks are easy to occur in welded parts.For the research of T-butt welded plate with cracks,the Stress Intensity Factor(SIF)is generally chosen as the evaluation parameter,the Finite Element Method(FEM)is used to evaluate the residual strength combined with the theory of linearelastic fracture mechanics.However,the corrosion of ships and offshore structures during the whole service period is an important factor that must be considered.The damage of crack and corrosion to structure is much greater than that of single factor.In this paper,on the basis of the study of T-butt welded plate with penetrating crack,considering the influence of non-uniform corrosion factors,the change rule of residual strength of T-butt welded plate under the combined action of crack and non-uniform corrosion is studied.Firstly,through the study of three-dimensional penetration crack,the accuracy of the calculation results of the FEM is determined.The main factors affecting the distribution of SIF along thickness direction are found,and the distribution diagram of SIF along thickness direction was established.Secondly,the T-butt welded plate with penetrating crack is established.The distribution rule of SIF along the thickness direction is calculated by FEM,then found the main factors that affect the distribution of SIF,and the position of the maximum value of SIF is determined.Finally,combined with the theory of Maximum Crack Opening Displacement(MCOD),a functional relation between the maximum value of SIF and the MCOD is established.Finally,because of the long calculation time and the complexity of simulated non-uniform corrosion in solid model,a new calculation method is established in this paper.The non-uniform corrosion surface created by fractal geometry is given to the simplified shell element calculation model.The calculation results of the non-uniform corrosion shell element model and the function relation between the shell element and the solid element are used to calculate the SIF of the solid element model under the non-uniform corrosion.Then,the solid finite element model of T-butt welded plate under non-uniform corrosion is established for verified the correctness of the above calculation method.Finally,combined with the linear elastic fracture mechanics criterion,the residual strength of cracked T welded plate under non-uniform corrosion is evaluated.