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Parametric modeling and contact analysis of helical gears with modifications
He Zeyin,Lin Tengjiao,Luo Tianhong,Deng Tao,Hu Qiguo 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11
An approach for a mathematical model and contact analysis of helical gears including tip relief, root relief, end relief and longitudinal crowning modification was developed. First, tooth profile equations of non-modified involutes, tip reliefs, root reliefs and fillets were derived after applying gear principles and coordinate transformation to transverse cross section profiles of a rack cutter. Then the intersecting lines between different profiles were solved through by Gauss-Newton numerical method. Parametric modeling program of modified helical gears was obtained to automatically generate exact gear surfaces of tip reliefs, root reliefs, end reliefs and longitudinal crowning modifications via Matlab code. Subsequently, an example of helical gear pair in practical engineering was presented, and the solid model and finite element model with modification were established. Finally, the dynamic contact characteristic of helical gear pair was calculated by three-dimensional dynamic contact finite element method. It is expected that the proposed approach can be applied in analyzing the effect of modification on radiation noise prediction of gear system in further study.
The nonlinear effects of flexible pins on wind turbine gearboxes
Xiangyang Xu,Shaojiang Dong,Jiayuan Luo,Tianhong Luo 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8
The structure of flexible pin-type planetary gear systems used in wind turbine gearboxes can improve the load sharing ability of planetswhile saving space unlike straddle-type carriers. However, the nonlinear dynamic characteristic of this type of system is not fully developed. This work presents a coupled lumped-parameter dynamic model to demonstrate nonlinear effects. Gear contact loss nonlinearityand bearing clearance nonlinearity are integrated into this dynamical model, and the effects of flexible pins on the nonlinear dynamicresponses are discussed. The conclusions made are as follows: lower flexible pin stiffness can significantly reduce nonlinear effects;when pin stiffness is increased, contact loss still occurs in positions of strong vibration even if the planet gear bearings have higher ordersof magnitude of tangential load in the wind turbine gearbox; dynamic response peaks are asymmetric with a frequency sweep; only leftoblique "Soft" jumps occur, and the right oblique “Hard” jump phenomena rarely occur; planet gear supporting the bearing clearanceexists; and vibration chaos occurs in positions of strong vibration.