Abstract:

：Fatigue pitting is one of the inherent features of gear’s wear mechanism. Accordingly, the morphological feature of pitting debris has been adopted in interpreting the occurrence and development of fatigue failure. However, the accordance of this practice has remained in experiential level due to the lack of theoretical support. Aiming at the on-line monitoring of fatigue pitting failure via particles, a numerical analysis of fatigue pitting process is proposed to extract the morphological features of pitting particles. A simplified local contact model of gears is constructed considering the condition of elasto-hydro dynamic lubrication (EHL). An extended finite element method (XFEM) is introduced to simulate the propagation of an initial micro-crack. A pitting process is simulated using the proposed method and the influences of boundary conditions on the morphological features of wear particles are analyzed. Results show that the major dimension of the pitting particle depends on both the length of the initial crack and the applied load. And its minor dimension depends on the length of the initial crack. To validate the effectiveness of the proposed model, some reported experimental results are adopted for comparisons. Similar dimensions of the calculated crack and the experimental one reveal the accuracy of the proposed model.

Key words: crack propagation, gear, wear debris, fatigue pitting