International audienceThe gear in an aero-engine experiences alternate loads therefore the stresses on gear root change significantly in meshing process. As a consequence, fatigue crack initiates on the gear root. This paper examined meshing process and crack propagation trajectory of the aero-engine gear based on explicit dynamics and linear elastic fracture mechanics. The crack on gear root affects meshing process and causes additional noise and vibration.The meshing impact and the peak of stress distribution of the gear pair is also magnified. Furthermore, the root crack propagation can cause the rim fracture and tooth fracture of gear system. The occurrence of rim fracture increases as the backup ratio (i.e., rim thickness divided by tooth height) decreases and also increases as the initial crack location is moved down the root of the tooth; the orientation of initial crack has little influence on crack propagation trajectory
