Dynamic characteristics and crack propagation path of low speed and heavy load gears

In order to solve the problems of dynamic characteristics and crack propagation path of low-speed and heavy-duty gears, the main contents are as follows:

1) Taking the low-speed and heavy-duty gear as the research object, the contact finite element model of the gear is established to study the contact characteristics of the tooth surface in the meshing process. According to the distribution law of the contact stress of the gear, the “most dangerous” area of the gear is defined as the fatigue crack initiation area.

2) According to the above results, the fatigue crack area is between the base circle and the tooth root circle, and the influence of the crack at the base circle and the tooth root circle on the natural characteristics of gears with different crack lengths is studied.

3) The variation of stress intensity factor (SIF) at the leading edge of gear root crack is studied, and the influence of crack size, crack shape and load on SIF is analyzed.

4) The crack propagation paths of gears with different crack positions and different crack angles are simulated, and the real three-dimensional crack propagation paths are studied.

In the study of three-dimensional gear, an accurate crack tooth model is proposed. When analyzing the stress intensity factor of leading edge and crack propagation path, the semi elliptical crack is used to reflect the shape of initial crack more realistically.