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Description

Split path gearboxes can be attractive alternatives to the common planetary designs for rotorcraft, but because they have seem little use, they are relatively high risk designs. To help reduce the risk of fielding a rotorcraft with a split path gearbox, the vibration and dynamic characteristics of such a gearbox were studied. A mathematical model was developed by using the Lagrangian method, and it was applied to study the effect of three design variables on the natural frequencies and vibration energy of the gearbox. The first design variable, shaft angle, had little influence on the natural frequencies. The second variable, mesh phasing, had a strong effect on the levels of vibration energy, with phase angles of 0 degrees and 180 degrees producing low vibration levels. The third design variable, the stiffness of the shafts connecting the spur gears to the helical pinions, strongly influenced the natural frequencies of some of the vibration modes, including two of the dominant modes. We found that, to achieve the lowest level of vibration energy, the natural frequencies of these two dominant modes should be less than those of the main excitation sources.

Publication Date

5-1995

Publisher

National Aeronautics and Space Administration and U.S. Army Research Laboratory, Cleveland

City

Washington, D.C. and Adelphi, MD

Keywords

vibration, dynamics, gears, bearings

Disciplines

Aerodynamics and Fluid Mechanics | Aerospace Engineering

Comments

NASA TM--106875

ARL--TR--723

AIAA--95--3048

Prepared for the 31st Joint Propulsion Conference co-sponsored by AIAA, SAE, ASME, San Diego, California, July 10-12, 1995.

Vibration Analysis of a Split Path Gearbox

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