Reliability Analysis Of Pressure Structure Of Submarine Based On Probabilistic Fracture Mechanics

As large casting,forging and welding parts, pressure structures of submarine would inevitably have some defects in the manufacturing process, such as porosity,inclusions and so on. There are many cases of failure of pressure structures of submarines caused by interior defects in the world. In general, there are the initial cracks near the weld toes of cone cylindrical shell of the submarine, in addition, thinking of the special mechanical characteristics, it became into the most dangerous fatigue failure site.In this thesis, the stress intensity factor which matched up to cracks in the weld toes of cone cylindrical shell was selected and corrected by considering the influence of compressing stresses,residual stresses,the stress concentration and the stress ratio. The reliability of brittle fracture at the weld toes of the convex cone cylindrical shell of the submarine was calculated using First Order Second Moment method and the Monte Carlo method. The results of the calculated example verified the feasibility of the First Order Second Moment method in computing the reliability of brittle fracture of pressure structure of submarine.In this thesis, it was proposed a solution which combined with general probabilistic fracture mechanics method and the Monte Carlo method tentatively. The results of calculated example showed that it is feasible to calculate the fatigue life reliability and remaining fatigue life in this solution.