Abstract: The thin-walled gear is a lightweight type with high power density, which is widely used in the aviation geared drivetrain. But the safety risk induced by the traveling wave vibration is prominent, and the dynamic theoretical model still needs to further clarify the response characteristics of forward and backward wave types. Therefore, a dynamic model for the thin-walled gear under meshing excitation is proposed to describe vibration characteristics of traveling waves, called elastic gear with moving loads (EGML) model: the virtual shaft equivalent method is used to degrade the complex gear tooth features, so as to obtain the equivalent regular structure; the gear rim, web and shaft are meshed by hybrid shell elements and Timoshenko beams; the gear pair is decoupled to expose the meshing force, which is a time-varying excitation relative to the gear rotation, and thus to establish a mathematical representation of the moving load to reflect its time-space variation characteristics; the meshing excitation acts on the flexible gear model, and the motion governing equation can be developed. Besides, the high-speed gear transmission experiment is conducted to verify the proposed method. Results show that the EGML model can accurately characterize the forward and backward wave type. It has this characterization ability after considering the web elasticity and the relative rotation between the excitation and gear. When the traveling wave vibration occurs, the displacement field is a petal distribution that fits the nodal diameter modal shape, and moves rapidly along the circumferential direction. This research provides a dynamic model that balances accuracy and efficiency to obtain the dynamic response of thin-walled gears, and is a theoretical basis for evaluating the impact of the traveling wave resonance, and can be used to guide the thin-walled gear design to avoid the resonance threat for its safe operation.

Key words: thin-walled gears, traveling wave vibration, elasticity model, moving loads, response characteristics