Publication Date

2010

Document Type

Thesis

Committee Members

Antonio Corvo (Committee Member), Jeffrey Dalton (Committee Member), Andrew Hsu (Other), George Huang (Other), Rory Roberts (Committee Member), Joseph Slater (Committee Member), J. Mitch Wolff (Committee Chair)

Degree Name

Master of Science in Engineering (MSEgr)

Abstract

To increase reliability and efficiency, standard aircraft components are being replaced with more electric subsystems aimed to reduce weight, conserve space, and improve energy management. One application of this process replaces standard hydraulic actuators used in flap or aileron movements with electromechanical actuators powered by an external generator. During different types of return movements, the electromechanical actuator will produce regenerative power that flows back through the generator and pulses into the engine-gearbox subsystem. The regenerative power, defined by characteristic amplitude, frequency, and other pulse attributes, coupled with the driving force produced by the engine may dramatically impact the performance and life of the gearbox.

Steady state and transient subsystem models have been developed in the MATLAB/Simulink® environment to simulate gearbox behavior subject to incurred engine loads, regenerative power loads, and other dynamic phenomena such as backlash present in the gear interactions. Employing a lumped inertia approach, derived equations of motion incorporate damping and stiffness parameters pertaining to bearings, shafts, and gear mesh interactions. Particularly sensitive to the amount of damping acting at the gear mesh, the contact force and inter-gear dynamics are modeled by three separate methods of contact force calculation. The models and development process utilized in this study can be used as practical gearbox design and scaling tools for other gearbox systems.

Application of regenerative energy causes instantaneous oscillations of the angular velocity and transient torque profiles of the gearbox components and connecting shafts. Several shafts experience high stress fluctuations and absolute reversal of rotation that possibly act as sources leading to accelerated fatigue failure. Depending on the applied method of contact force calculation, instances of gear backlash at engine start-up conditions are experienced. Regenerative transients cause variations in the amount of inter-gear penetration, but backlash never occurs for any gear pair operating at the provided conditions.

Page Count

266

Department or Program

Department of Mechanical and Materials Engineering

Year Degree Awarded

2010

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