A Computational Model for Bending Fatigue Analyses of Sintered Gears

A computational model for determination of the fatigue life of sintered gears in regard to bending fatigue in a gear tooth root is presented. The proposed model is based on the stress-life approach in which the multi-axial state of stress, the mean stress effect, the influence of surface roughness, and the notch effect are studied when determining the fatigue life of a treated gear pair. The required material parameters (the fatigue strength coefficient sigma(f)' and the fatigue strength exponent b) are determined experimentally on a uni-axial tension/compression test machine with a load ratio of R = 0. Here, the influence of additional thermal treatment (after sintering) on the fatigue strength is studied. The model is used for the determination of the fatigue life of real spur gear made from a Hoganas Distaloy AB powder mixture, while the stress field in a gear tooth root is determined numerically using the FEM method.