Analysis of lubricating performance for spur gear pairs applying tribo-dynamic model

Abstract

A tribo-dynamic model for spur gear pairs combined dynamic loading with elastohydrodynamic lubrication theory is proposed in this paper. The integrated model incorporates a transverse-torsional dynamic model and a mixed elastohydrodynamic lubrication model to predict the dynamic behavior and lubricating performance of a spur gear pair under typical operating conditions. The dynamic model considering time-varying mesh stiffness, backlash as well as friction force generated from contact surfaces is built up to predict the dynamic tooth forces and surface velocities for the elastohydrodynamic lubrication model. In return, the elastohydrodynamic lubrication model taking into account the transient effect provides the dynamic model with viscous damping, friction forces and moments that play a non-negligible role in free and forced vibrations. In view of the convergence and efficiency, an iterative calculation program combined Runge-Kutta method and the multigrid method is developed to implement the tribo-dynamic model orderly to investigate the mutual relationship between the two models. The elastohydrodynamic lubrication predictions of the proposed model under dynamic conditions are compared to those obtained from a quasi-static elastohydrodynamic lubrication model to demonstrate the influence of the coupling effect on the elastohydrodynamic lubrication behavior. Simulation results indicate that the vibration caused by time-varying gear mesh force may enhance the friction coefficient at high speed.