An experimental analysis of the dynamics of minimally damped, subcritically excited gear pairs

This paper investigates, through experimentation, the inherently nonlinear dynamics that meshing gear pairs display. The experimental rig consists of 1:1 ratio high-module spur gears connected to high precision encoders. The amplitude of a displacement fluctuation input is varied and the relative motion of the two gears is recorded. The experimental trajectories show at least two stable impacting regimes for each fluctuating input amplitude, differing in the magnitude of the relative angular displacement. The amplitude of motions is sometimes comparable to the backlash size, and for some parameters both noisy solutions with large relative displacement amplitudes and quieter, smaller amplitude solutions may occur. A simple single degree of freedom model is derived, based upon a combined constant velocity and fluctuating displacement input. This model is compared with experimental results in order to understand fundamental contact mechanics. Solutions to the mathematical model are generated using a numerical integrator and predict the maximum relative displacement amplitude motions accurately, but not the smaller amplitude motions. This is because the model omits and simplifies certain mechanisms such as meshing impacts and gear eccentricity, both of which will be added in future investigation.