Contact stiffness and dynamic behavior caused by surface defects of spiral bevel gear in mixed lubrication

Abstract

Geometric defects may occur on the gear surfaces during manufacturing and service, such as pitting. However, the defect is rarely incorporated into gear mesh analysis. In this study, a transient mixed lubrication model and a two-dof-torsional dynamic model are proposed for spiral bevel gears, wherein the time-varying contact parameters and the defect on the meshing path are all considered. First, the time-varying contact parameters are calculated by Tooth-Contact-Analysis (TCA). After that, by simulating the gear meshing process, an engineering rough surface with a circular defect moves through the contact region. The transient mixed lubrication performances with the consideration of surface defect are obtained including the film thickness and pressure along the meshing path. Based on this, the normal stiffness of single tooth from engaged-in to engaged-out can be calculated through the normal contact deformation. Finally, the dynamic responses of gears are analyzed according to the normal stiffness through a two-dof-torsional model. Numerical results show that the surface defect has a significant effect on the meshing process of spiral bevel gears and the dynamic response also changes with the size, depth and location of the defect. This provides a theoretical reference for identifying early failures caused by defects based on dynamic signals.