Research trend of root crack of spur gear

At present, simplified models are used in the research of fatigue crack of spur gear tooth root. In these simplified models, the load is simplified as ideal uniform load or as concentrated force load at a point on the tooth top; This load simplification method is far from the actual situation. Considering the uneven load distribution in the tooth direction, the specific research contents are as follows:

(1) The research status of fatigue crack theory is summarized, and the research status, shortcomings and trend of tooth root crack are also summarized. In the second chapter, the theoretical knowledge of crack propagation and life prediction is introduced. This paper is based on linear elastic fracture mechanics. Therefore, in this part, only the relevant knowledge of linear elastic fracture mechanics is given, and the relevant knowledge of elastoplasticity is not introduced.

(2) The solid model of spur gear is established by using ANSYS APDL language. Considering the symmetry between spur gear teeth, a tooth is selected as the research object, a single tooth finite element model is established, and the initial crack position is determined through static analysis; The single tooth finite element model with load applied in ANSYS is introduced into FRANC3D, and the initial crack with shape and size is embedded in the dangerous position of tooth root.

(3) Considering the different loads between the points on the contact line in the meshing process of the actual spur gear, the load linearly varying in the tooth width direction is applied to the contact line in the process of simulating the crack propagation of the tooth root; The variation laws of stress intensity factor, crack offset angle and fatigue life of spur gears are analyzed. The results are compared with those under ideal uniform load, so as to illustrate the influence of uneven tooth load distribution on crack propagation path and fatigue life of spur gears.

(4) Due to the complexity of crack initiation, considering the crack at different parts of the tooth root, the crack propagation process is simulated, and the different stress intensity factors of the initial crack front at different positions are calculated; Then the crack propagation life under different crack positions is predicted. Finally, the influence of different positions on the crack propagation life of spur gear is discussed, and the regular results are obtained.

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