A simplified prediction model of dwell-fatigue crack growth behaviour for titanium alloy

It is observed that the dwell-fatigue cracks grow faster than the fatigue cracks for the titanium alloys. The dwell-fatigue behaviours have a great influence on the accurate life prediction of submersible pressure hulls. A modified model is proposed to predict the dwell-fatigue crack growth behaviour of titanium alloys under different dwell times and ratios in this paper. Based on the predicted model advanced in the authors’ group, the crack tip plastic zone is modified by introducing the crack tip plastic induced by the dwell time in the modified model. The parameters of the crack tip plastic zone induced by the dwell time are determined by the room temperature creep tests. The fatigue and dwell fatigue crack growth rate of the two titanium alloys under different stress ratios and different dwell times are predicted successfully by the modified model. The model is validated by comparing model prediction results with the experimental data.