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Mathematical Problems in Engineering
Volume 2015 (2015), Article ID 381010, 15 pages
Research Article

Load Sharing Multiobjective Optimization Design of a Split Torque Helicopter Transmission

1School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, China
2Systems Engineering Division of China Academy of Launch Vehicle Technology, China Aerospace Science and Technology Corporation, Beijing, China

Received 2 April 2015; Accepted 18 May 2015

Academic Editor: Dapeng P. Du

Copyright © 2015 Chenxi Fu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Split torque designs can offer significant advantages over the traditional planetary designs for helicopter transmissions. However, it has two unique properties, gap and phase differences, which result in the risk of unequal load sharing. Various methods have been proposed to eliminate the effect of gap and promote load sharing to a certain extent. In this paper, system design parameters will be optimized to change the phase difference, thereby further improving load sharing. A nonlinear dynamic model is established to measure the load sharing with dynamic mesh forces quantitatively. Afterwards, a multiobjective optimization of a reference split torque design is conducted with the promoting of load sharing property, lightweight, and safety considered as the objectives. The load sharing property, which is measured by load sharing coefficient, is evaluated under multiple operating conditions with dynamic analysis method. To solve the multiobjective model with NSGA-II, an improvement is done to overcome the problem of time consuming. Finally, a satisfied optimal solution is picked up as the final design from the Pareto optimal front, which achieves improvements in all the three objectives compared with the reference design.