## 3 Calculation Results and Discussion  
### Influence of Chamfer  
The time-series stresses were obtained by multiplying the time-series loads with the STM of each node. The time-series shear stress was extracted. The fatigue damage of each node was obtained using the constant-amplitude life diagram of the material and linear damage superposition principle. A structural configuration was selected as the benchmark model to evaluate the influence of various structural configurations on shear fatigue. The structural configurations of the benchmark model are shown in Table 1.  
The shear fatigue damage results of this model are shown in Figure 13. The horizontal axis represents the position of elements, arranged from the leading edge to the trailing edge, and the vertical axis represents the logarithmic expression of the damage. Figure 13 shows that the damage of the adhesive closer to the leading edge and the damage closer to the PS were more serious.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Structural Configuration** & **Detail** \\ \hline Position of UD & 20 mm \\ Whether there is outer over lamination & Yes \\ Prefabricated component & Prefabricated filler \\ Chamfer & Straight and perpendicular to the bonding surface \\ \hline \hline \end{tabular}
\end{table}
Table 1: Structural configurations of the benchmark model.  
Figure 12: Flow chart of the calculation process of damage.  
The results of other structural configurations were compared with the results of the benchmark model. The chamfered forms of each model are shown in Figure 5b-d. The model in which the angle between the chamfer surface and the bonding surface of PS was obtuse was named BBL1. The model in which the angle between the chamfer surface and the bonding surface of PS was acute was named BBL2. The main difference between BBL models and the benchmark model was the chamfered forms at the beginning of the bonding line. The other parameters were the same.  
Figure 14a,b shows the damage of the BBL1 and BBL2 models, respectively. The difference between the results of the two models was reflected mainly at the beginning position of the bonding line.  
Figure 15 shows a comparison of the damage distribution along the thickness of the three models at the beginning of the bonding line. BBL2 had the maximum damage and BBL1 had the least damage on the first layer. Vice versa was the case on the fifth layer. The damage near the pressure side (layer 1) and prefabricated component (layer 5) was closely related to the angle of the chamfer. If the angle of the chamfer near the bonding surface was acute, the damage increased. If the angle of the chamfer near the bonding surface was obtuse, the damage reduced.  
Figure 14: Damage of two other models with different chamfers: (a) Damage of the BBL1 model; (b) Damage of the BBL2 model.  
Figure 13: Damage results of the benchmark model: (a) Damage of the adhesive in the benchmark model; (b) Layer number of the adhesive mesh.  
The damage comparison results of different chamfers showed that the angle of the chamfer at the end of the bonding line should be obtuse, whether in the production or in the maintenance of blades. Generally speaking, the angle between the adhesive extruded naturally, and the bonding surface was acute when the blade mold is closed. If not treated, obvious stress concentration occurs at the bonding line, leading to high fatigue damage. One way to deal with the bonding line, which is not the only way, is to make a scraper. The scraper with a certain shape can be made before blade production and maintenance. After the completion of mold closing or bonding, the excess extrusion adhesive can be scraped away using the scraper. On the one hand, the unnecessary weight in the blade can be reduced. On the other hand, the stress concentration of the bonding line can be reduced.