New approach for gear mesh stiffness evaluation of spur gears with surface defects

Abstract

Gear tooth surface fatigue is one of the most common failure modes of gears. Surface fatigue manifests on two principle phenomena, namely spalling and pitting. Spalls are localized cavities on the teeth surface with relatively important depths, whereas pits are distributed cavities on all the teeth surface with small depths. Generally, spalls and pits appear with nonuniform shapes, making their modelization difficult for researchers. Therefore, common methods assume specific geometries (rectangles, triangles, circles, etc.) to consider surface defects on the gear mesh stiffness evaluation process. In this paper, a new method has been proposed to accurately calculate the gear mesh stiffness of spur gears with surface defects based on the potential energy method. A double discretization of the tooth surface was performed to consider defect depth variation in both width and length directions of the gear tooth. A contact detection algorithm is developed to detect actual contact points during meshing process. Simulation results showed that the deformation of the gear mesh stiffness due to irregular shaped spalls and pits was completely different to those of regular shape and depends on the defect severity. In addition, results showed that the spall size and position have an impact on the final deformation of the gear mesh stiffness. The proposed method allowed remedying to multiple problems exposed by researchers in modeling gear mesh stiffness of gears with tooth surface defects.