The finite element software is used to simulate the helical gear with three-dimensional cracks, and the values of stress intensity factor and J-integral under three different initial crack parameters of different loads, different lengths and different positions are calculated, so as to explore their variation law.
(1) When only one of the initial crack parameters is changed, the numerical distributions of stress intensity factors K1, K2 and K3 have their own changing rules. However, when the three different initial crack parameters are changed, only the numerical distribution of stress intensity factors K1 is similar to the quadratic function image. In the helical gears with initial three-dimensional cracks, K1 stress intensity factor is dominant, while K2 and K3 stress intensity factors are relatively small. In the case of only changing the initial position of the crack, when the crack is farther along the positive direction, the change of K1 stress intensity factor is not obvious, while K2 and K3 stress intensity factors increase in the positive direction. Therefore, K2 and K3 stress intensity factors should not be ignored when studying the three stress intensity factors of helical gear.
(2) The results show that the distribution of J-integral is approximately parabola at the crack front. When only changing the initial crack parameters of the same type, the distribution of K1 stress intensity factor and J-integral has the same change rule.
(3) Combined with the change law of stress intensity factor and J-integral, the fatigue fracture life and the crack initiation and instability of parts can be better studied and explored, which provides a certain reference value for the study of fracture analysis and life prediction of helical gears.