Eq. (17) was drawn in Fig. 9 which showed a relatively good correlation with the experimental date and the forecasted curve. Therefore, it was considered that the S-N curve of Eq. (1) sufficient and logically describes the physical characteristics and phenomenological quantitative rules of fan blades. What counts was the parameters of the model can be conveniently and easily determined. As shown in Fig. S4 it could be seen that the fatigue failure mode of the measured fan blade could be considered as a feature of fatigue crack initiation and propagation, starting from the edge angle of blade root to the penetration and fracture of blade root.