Dynamics modeling and analysis of planetary gear mechanism under mixed elastohydrodynamic lubrication

Mixed elastohydrodynamic lubrication is the main lubrication style of planetary gear mechanism. In this paper, the dynamic characteristics of planetary gear mechanism under mixed elastohydrodynamic lubrication are investigated using a computational methodology. First, the mathematic model of mixed elastohydrodynamic lubrication is proposed, in which the scaling factors are introduced to depict the balance between the asperities and the oil film. A stiffness formula of the oil film is presented to describe the time varying stiffness of the teeth pair. Then, the stiffness of the oil film and the general stiffness are obtained. Finally, dynamic model of the planetary gear mechanisms is established and the dynamic responses of planetary gear mechanism are analyzed. The influences of operational parameters on stiffnesses and dynamic characteristics of the planetary gear mechanisms are investigated. The simulation results indicate that the nonlinear dynamics characteristics are significantly influenced by the lubrication conditions.