Coupling of dynamics and elastohydrodynamic lubrication for spur gear

A six-degree-of-freedom tribo-dynamics model for spur gear pair was proposed based on the load sharing theory and dynamics theory. Time-varying mesh stiffness and film stiffness, surface roughness as well as the friction torque were considered for establishing the model. A decoupling method was used to solve the tribo-dynamics model. In the iterative loop, the tribo-dynamic model predicted the dynamic tooth forces and surface velocities and applied into the lubrication model. In return, the gear lubrication model provided the tribo-dynamic model with friction coefficient and film stiffness. An example of gear pair was analyzed using the proposed model and method to demonstrate the coupling relationship between tribological and dynamic behaviors. The results show that total gear stiffness decreases slightly with consideration of coupling effect.Sliding friction force has significant effect on dynamic response that's perpendicular to action line.Dynamic load will affect oil film thickness, portion of load carried by film, film temperature rise and the friction coefficient greatly. Moreover, the effect of dynamic behavior on film temperature rise depends on the relative sliding velocity.