Probabilistic fracture mechanics based fatigue evaluation of ship structural details

Present ship building rules follow SN curve approach to evaluate the fatigue damage at identified locations while use of fracture mechanics approach is yet to receive due attention. In the present work, a methodology of evaluation of fatigue life of the longitudinal stiffener and transverse web frame connection using fracture mechanics has been demonstrated. Since, various factors such as the crack dimensions, the crack growth law parameters and the applied loads are random in nature; they have been accounted for considering their randomness. Numerical results obtained with the present method for fatigue life of an oil tanker are compared with those based on IACS Common structural rules and a good agreement is observed between them. The present method may find useful application to risk based inspection of ship structures.

► Fatigue evaluation method using fracture mechanics for oil tanker detail outlined.
► Randomness of crack dimensions, crack growth parameters and loads considered.
► Fatigue lives are positively skewed with high c.o.v [35–50%].
► Choice of the input parameters strongly influences the calculated fatigue life.
► Fatigue life predictions agree well with IACS CSR based fatigue evaluation.