Verification of stress transfer mechanism in fatigue crack growth under overload

Cyclic plastic finite element modeling was carried out to investigate effect of overload on fatigue crack growth under blunting and no-blunting mechanisms at different overload ratios. The stress transfer mechanism was verified and was found more obvious in the case of crack blunting though its effect was time-limited. The level of crack closure varied periodically due to gradual relaxation of compressive residual stress during crack propagation. Both the overload plastic zone and the overload affected zone were linearly correlated with overload ratio, and an overload ratio value of 1.1 was the best choice for studying overload effect.