Nonlinear random vibration of planetary gear trains with elastic ring gear

Kahnamouei, Jalal Taheri (2021) Nonlinear random vibration of planetary gear trains with elastic ring gear. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (8MB)

Abstract

Planetary gear trains (PGT) are widely used in the field of renewable energy, especially in wind turbines. A wind turbine uses planetary gearboxes to transfer wind torque to a generator, and even though gearboxes are designed according to sound engineering practices, they fail much sooner than their design life estimates. Unexpected PGT failures are costly, and it is vital to detect these failures early. This thesis proposes proper methods and analyses that help the wind turbine industry to prevent future failure by enlightening the nonlinear dynamic behavior of PGT under random force. This thesis will investigate one of the main factors in PGT failure: random vibration caused by wind turbulence. In this thesis, a hybrid dynamic model was proposed to model the stochastic nonlinear dynamics of a PGT with an elastic ring gear, and then the statistical linearization method (SL) was introduced to linearize the model. A new criterion of the SL is introduced to linearize the stochastic nonlinear dynamic model of a gear pair. The stochastic response of a thin-walled ring gear PGT under three equally-spaced random moving loads was also investigated. A series of parametric studies was conducted, and the obtained results revealed that the proposed model for the PGT accurately represented the dynamic behavior of the PGT with an elastic ring gear, and the SL gave acceptable accuracy. Also, the energy-based SL was enough accurate and valid to apply to stochastic nonlinear gear pairs under heavy load conditions, and the accuracy of the SL decreased for light load conditions. Finally, analysis on the effect of random moving loads on the ring gear showed that the mean of displacement was affected by the critical speeds, and random loads' speed does not influence the standard deviation of displacement. Monte Carlo simulations (MCS) were conducted to verify the proposed model and method, and MCS proved the accuracy of the proposed model and process.

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