Abstract: Aiming at the problem that the high fatigue damage of the shaft with locking thread segment structure mainly concentrated on the thread, in order to reduce the fatigue damage value of the position, the influence of the shaft structure on the fatigue strength of the locking thread section was analyzed. On the premise of retaining the thread structure and ensuring the mechanical properties, the correct mathematical model was established by using finite element software and nCode software. Through changing the parameters such as the width and depth of the main shaft unloading groove, the distance between the thread segment and the large end of the main shaft, and the radius of the arc behind the thread segment, the influence of these parameters on the fatigue damage value of the locking thread segment was analyzed. The results show that the fatigue damage value can be reduced by changing the width and depth of the unloading groove within a certain range, and the fatigue damage value increases exponentially after exceeding a certain range. The farther the thread segment is from the large end of the shaft, the lower the fatigue damage value is, and the smaller the radius of the arc of the thread segment is, the greater the fatigue damage value is. The analysis results provide a reference and basis for the structural design of wind turbine main shaft, which has certain engineering practical value.

Key words: wind turbine; main shaft; locking threaded section; fatigue strength