Dynamic modelling and analysis of split-torque face-gear systems

Aydoğan, Mustafa Özgür
In this study it is aimed to develop a dynamic model for a face-gear drive system that accounts for all important physical parameters related to the operation to achieve an optimized split-torque face-gear based transmission system. With this new model, nonlinear dynamic response of a face-gear drive system is sought and dynamic stability and limit states of this structure are investigated. The main motivation for the current study is the recent development and utilization of face-gear drive systems in the helicopter industry. Face-gear drive systems are subject of many research studies for the past 30 years. However, mesh stiffness of the face-gear is not modelled accurately. In this study, a nonlinear dynamic model of a multi-mesh involute spur pinion driven face-gear split-torque drive system is developed. A lumped mass system consisting of five pinions and two face gears is constructed. The system has seven rotational degrees of freedom. All pinion and gear blanks are assumed to be rigid disks. The constructed split-torque model includes two input, two output and three idler gears. The mesh parameters, i.e., mesh stiffness and mesh damping, have time varying characteristics. The model includes clearance-type nonlinearity for backlash. The proposed model calculates the time varying mesh stiffness of the gear pair from the generated point clouds of the face-gear and spur-gear pair by using the finite strip method (FSM). The nonlinear equations of motion are solved with Harmonic Balance Method (HBM) for periodic steady state response of the system. The accuracy of the results is compared with direct numerical integration solutions. The stability is checked with Floquet Theory and bifurcation diagrams from Poincare Sections. The effects of mesh phasing between each pinion and face-gear engagement, the effect of static torque and the effects of backlash variations to the response of the system are sought. The effect of subharmonic motion on the dynamic response is demonstrated. Also, torque-split characteristics of the system has been sought.


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Citation Formats
M. Ö. Aydoğan, “Dynamic modelling and analysis of split-torque face-gear systems,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.