Research Status of Gear slap Dynamics at China and Abroad

Among domestic scholars, Feng Qi and others have studied the slapping vibration of random AM secondary drive, directly adopted non-Gauss truncation technology, derived a discrete stochastic model described by mean mapping, revealed the nature of random model of random AM secondary drive by means of average Poincare diagram and power spectrum density of average velocity, and given chaos emission by means of maximum Lyapunov index.Generate parameter fields.Dong Haijun et al. established a centralized mass model for the analysis of rattling vibration of single-gap gear system taking into account the torque fluctuation of drive shaft and the backlash of gear pair teeth side.

The velocity mapping relationship before and after collision of gear pairs was given by means of collision dynamics principle.The large single-cycle, chaos, periodic or quasi-periodic vibration and bifurcation characteristics caused by the variation of excitation amplitude are studied.Zhang Lochuai et al. established the dynamic equation of the second-stage gear system with time-varying engagement rigidity, which is a linear dynamic system with time-varying coefficient. The influence of torque fluctuation and time-varying engagement rigidity on the speed of slapping threshold was studied by using operator decomposition method (AOM).

The automotive transmission system can generally be viewed as consisting of two subsystems: flywheel-clutch and gear drive.At first, Sakai et al. expressed it by a centralized parameter model with five degrees of freedom; later, it was expressed by a centralized parameter model with four degrees of freedom, and the feasibility of this model was proved.This Four-Degree-of-Freedom centralized parameter torsional vibration mechanical model is composed of four centralized mass elements of flywheel, clutch, active and passive gears, elastic elements and damping elements, in which the mass elements of active and passive gears are the sum of the equivalent mass of each active and passive gear in the system.In the above analysis model, three non-linear factors, multi-stage clutch stiffness and gear pair backlash are included.

In terms of evaluation criteria of gear flapping intensity, Singh et al. put forward evaluation method based on angular acceleration of active gear. Johnson et al. found the source of flapping noise and quantified the noise objectively by experimental method. It is considered that analysis of gear movement and surface vibration of box is a better evaluation method of flapping noise.Padmanabhan et al. also proposed a beat index to objectively evaluate the noise level.Pfeiffer et al put forward a method of evaluating rattle index based on gear impact recovery coefficient.

In terms of noise reduction of slapping noise, Sebulke analyzed in detail the advantages of dual-mass flywheel over common flywheel, believing that it acts like a low-pass filter and can absorb irregular torsional vibration in the drive chain.Drexl discussed the role of common torsional dampers in reducing knock noise and proposed an alternative to dual-mass flywheel.Padmanabhan and Singh studies suggest that tapping noise can be reduced by properly adjusting clutch spring stiffness.

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