Torsional Stability of a Face-Gear Drive System

This paper establishes a structural dynamics model for torsional vibration of gearboxes containing a face-gear drive by considering flexibilities of gear teeth and transmission shafts. This model includes the time-varying gear mesh resulting from the unique face-gear meshing kinematics and non-unity contact-ratio. The gear mesh induced parametric instability phenomena are explored numerically by Floquet theory for various shaft characteristics and system inertia distributions. The results provide information to develop possible passive and active vibration suppression strategies via adjusting shaft stiffness and damping as well as changing inertia ratios of face-gear and output load to pinion. In addition, Tregold's approximation is employed for face-gear contact-ratio calculations to avoid complex numerical computations. For design purposes, a perturbation technique is utilized to predict stability boundary analytically for the cases with small system damping and small time-varying components of stiffness.