Prediction Of Fatiguelife And Reliability Of A Typical Detailin Ship Hull

Fatigue is one of the main reasons which cause ships and navalarchitectures failure. With the increasing of the ship hull, more and morehigh tensile strength steel will be used in the ship structure. The fatigue ofship structure will be more serious. In this paper, the fatigue crack growthprediction method will be used to predict the fatigue life of a typicaldetail in ship hull,and the processes of the reliability index calculationbased on the S-N curves and the crack mechanics respectively are appliedfor the same typical detail. It includes following works:1) The Green's function method is introduced to solve the stress intensityfactor of a central through crack in a infinite plate which is subjected toseveral typical loadings and polynomial distributed loading on cracksurface respectively. The calculated results were validated by comparingwith FEA results.A feasible study on Green's function method to calculatethe stress intensity factor of a single edge crack which is subjected toarbitrary distribution loading on its crack surface is performed.2) Several typical fatigue crack growth rate models,especially the uniquefatigue crack growth rate model for random loading, have been discussed.3) The prediction for the fatigue life of a surface crack at weld toe ofT-shape weldment under constant amplitude fatigue loading hasperformed. By Combining the stress range calculated by CCS hullstructure fatigue strength guide and the crack growth prediction methodbased on the unique crack growth rate curve, the fatigue lives of a detailon top deck and a detail on double bottom hull have been calculated.4) The reliability theory applying in the shipping and Marine structures issummarized. taking a typical detail of ship hull for demonstration, theprocess to calculate the reliability of ship structure is introduced. Theprocesses of the reliability index calculation based on S-N curves and thecrack mechanics respectively are given. Finally, the reliability indexchange with the stress range is used to give a demonstration of thereliability index as a detail structure optimization standard...