Simulation of fatigue failure on tooth flanks in consideration of pitting initiation and growth

Gears are used under demanding conditions which lead to a continuous change of the tooth surface. With an increasing operation time, appearances of fatigue, like micropitting, can be noticed. Micropitting is characterized by micro-cracks in the surface. In some cases, these cracks grow or join to networks and in combination with subsurface caused stress intensities, e.g. at microstructural defects in the material, this leads to macroscopic pittings, which end the serviceability of a transmission. This contribution defines micropitting and pitting and analyses their interaction and interdependency. A fatigue simulation for these mechanisms is introduced. Results of test rig trials and material analyses are presented and have been used to research these mechanisms, their interaction and also to validate the simulation.