The factors affecting crack growth studied by ZHY gear senior engineer team, such as stress ratio, corrosion environment, crack body size and initial crack size, are introduced. When studying the fatigue life and crack propagation law of pressure vessel, the influence of long short axis ratio of semi elliptical sheet crack on crack propagation life is considered. There are many factors that affect the crack propagation behavior and propagation life. It is necessary to select the factors to be considered according to the actual situation, and ignore the factors that are not important under the specific analysis.
Considering the influence of crack location on crack propagation behavior and crack propagation life, the different crack location of spur gear will affect the change of stress field at the crack front, thus affecting the size of stress intensity factor and further affecting the crack propagation life. These results are obtained through the joint simulation of fracture mechanics theory, ANSYS and FRANC3D.
The research on the factors affecting the crack propagation behavior and crack propagation life is the focus of the fatigue crack research of spur gears. With the different actual working requirements of components (such as working conditions, working environment, etc.), the factors affecting the crack propagation behavior and crack propagation life will also change. Generally speaking, these factors are very complex. It is impossible and unnecessary to fully consider all factors. The influence of the initial crack position, that is, the angle between the semi elliptical sheet crack plane and the XZ plane, on the fatigue crack propagation life of spur gears is considered.
Four kinds of initial cracks at different positions are embedded in the tooth root, the propagation process of the tooth root crack at different initial positions is simulated, and the variation curves of Ki, Kii and kiII factors with the crack propagation length are obtained. The fatigue life of spur gears with initial cracks at different positions is predicted by using the results of stress intensity factor. It is concluded that the greater the angle between the initial crack plane and XZ plane, the longer the fatigue crack propagation life of spur gears, and the variation of two adjacent curves increases with the increase of the angle; Finally, the function of crack propagation life with crack propagation length (depth direction) at different positions is fitted, and the results are further discussed.