A New Helicopter Transmission Model for Condition-based Maintenance Technologies Using First Principles

Report No. ARL-TR-4984
Authors: David B. Stringer, Pradip N. Sheth, and Paul E. Allaire
Date/Pages: September 2009; 30 pages
Abstract: This report presents a new helicopter transmission model in support of condition-based maintenance (CBM) initiatives. The model uses the first principles approach to analyze the rotating shafts and gear couplings using rotor dynamic analysis techniques. The helicopter transmission is presented, followed by a discussion of the finite element formulation to include gear mesh modeling methodologies. System natural frequencies and mode shapes are discussed, along with the model's validation procedure. The model's primary purpose is to simulate multiple operating conditions to include faults. One such fault condition simulates the wear of gear tooth contact surfaces. The nature of the fault and its modeling techniques are discussed. Simulation results are presented in the time domain using a conventional vibration diagnostic parameter. A new diagnostic parameter, the FE2, is also introduced for detecting faults in the frequency domain. Additional considerations and further research points are also discussed. The results demonstrate the potential of physics-based, mathematical models in providing a key technology enabler for improving health monitoring and prediction capabilities of CBM strategies.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2009