Geometrical complexity and crack trajectory based fatigue life prediction for a spur gear having tooth root crack

Abstract The objective of the present study is to perform a three-dimensional crack propagation path analysis for different geometrical parameters of spur gear tooth and study its implications on fatigue life of gear. Most of the study for crack trajectories in gear tooth has relied on a 2-Dimensional platform to formalize these simulations which have resulted in undermining various factors encountered in the studies. This paper proposes a three-dimensional Boundary Element Method (BEM) based approach to generate the crack propagation trajectories. A three-dimensional linear elastic fracture mechanics based software; FRANC3D has been adopted to obtain the crack propagation path in a spur gear tooth root under influence of varying gear parameters. Crack Opening Displacement (COD) approach is used to determine the respective Stress Intensity Factor (SIF) for various modes. Moreover, the maximum tangential stress crack extension criterion is used to obtain the propagation paths. The fatigue crack in the gear tooth is subjected to constant amplitude moving load and the remaining service life is estimated by Forman-Newman-de Koning (FNK) model. The obtained fatigue life plots are compared with the previous studies in the literature to justify the simulative process.