A novel modeling method for evaluating the time-varying mesh stiffness of gears with pitting based on point cloud processing algorithm

The research on the time-varying meshing stiffness (TVMS) of gears provides a theoretical basis for the extraction of fault features. Pitting is a common tooth surface fault that has a significant effect on the TVMS. In this paper, a modeling method for evaluating the TVMS of gears with irregular-shaped pitting is proposed to replace the previous modeling methods by which pitting is reduced to simple geometry such as rectangles and cylinders. By the proposed method, the irregular-shaped pitting in analytical models can be matched with that of real objects and 3-D models in CAD software. Firstly, referring to the idea of reverse modeling in reverse engineering, the point cloud is used to map the real objects and 3-D models in CAD software to the analytical models. And a special point cloud processing algorithm is proposed to accurately calculate the TVMS. Then the coupling between multiple teeth with pitting is further investigated. The distribution and expansion of pitting are assumed to be 2-D normal distribution and random expansion. In addition, a complete system is established by taking into account of the gear body structure coupling effect, the nonlinear Hertzian contact stiffness, the accurate transition curve, and the tooth profile modification. Eventually, validation and discussion are conducted and it is demonstrated that the TVMS obtained by the proposed method is largely consistent with that calculated by the finite element method.