Total fatigue life prediction for Ti-alloys airframe structure based on durability and damage-tolerant design concept

Based on the concept of the damage-tolerance and durability design, the total fatigue life of titanium alloys is divided into three phases: crack initiation (0–0.3 mm), short crack growth (0.3–2 mm) and long crack growth (2 mm–a_C). Among these three phases, different prediction models are accepted due to different failure mechanisms. A computer program was developed to predict the total fatigue life of the titanium alloy structure. Fatigue testing is also conducted for two types of ELI grade titanium alloy to verify the prediction models. The predicted fatigue life agrees well with experimental results.