Study on crack initiation of harmonic gears based on extended finite element method*

The failure of the flexible wheel is the most important factor affecting the life of the harmonic reducer. In this paper, the harmonic gear which is widely used in the field of robotics and aerospace is taken as the research object. The basic principle of the extended finite element method has been discussed. Then, the involute harmonic drive is modeled and loaded, and the area of maximum stress is obtained as the crack initiation position. Further, the damage model of the harmonic gear is established based on the extended finite element method, and the rim crack growth path of the flexible wheel is observed. And the influence of crack parameters on the propagation path has been discussed. Finally, the high power to weight ratio harmonic reducer is machined and tested.