Submarine pressure hull butt weld fatigue life reliability prediction method

• The probability density evolution method is employed to predict submarine pressure shell butt weld fatigue life reliability.
• The crack size probability density function is figured out by the probability density evolution equation.
• The probability density evolution equation is derived by introducing extended state vector into crack propagation rate model.
• This method is suitable for fatigue life reliability prediction with random material properties under random loading.

As stress intensity factor for submarine pressure hull butt weld is very complicated, it is difficult to use common structural reliability analysis methods such as first-order second-moment method to predict its fatigue life reliability under stochastic loading. In view of the circumstance mentioned above, the probability density evolution method is employed to predict submarine pressure shell weld fatigue life reliability in this paper. State equation of crack propagation rate model with random initial conditions constructed by introducing extended state vector, then crack propagation growth probability density evolution equation is derived. Numerical method is used to solve the crack size probability density function in order to predict submarine pressure hull butt weld fatigue life reliability. The example shows that the result form proposed method is in good agreement with form Monte-Carlo method and crack size probability density function evolves with loading cycle.