Transmission vibration and noise have been studied abroad for many years, and some remarkable achievements have been made. First of all, for the research of gear noise generation mechanism, Tadashi Takeuchi, Sarah Curtis and others mainly made a detailed study and Analysis on the generation of transmission error and the influencing factors. Through the method of combining CAE model with measurement bench, the prediction and optimization method is finally put forward. This method provides a direction for judging the gear noise excitation source and early prediction optimization.

For the research on the vibration of gear system, Bollinger and Harker studied the influence of the change of gear stiffness on gear vibration. W. Through the research and analysis of planetary gear transmission, e palmery and Fuehrer et al. Studied and analyzed the planetary gear transmission, in order to change the gear profile modification parameters of the planetary gear, change the fitting frequency of the planetary gear when working, further achieve the purpose of avoiding the natural frequency and resonance, and finally achieve the goal of reducing vibration and noise for the planetary gear transmission. In the speed torque torque coupling system, ariii and watsubo assumed that the meshing stiffness of gears changed periodically, and the relationship between the vibration overlap coefficient and the dynamic stability zone of gears was established. K. Umezawa et al. Calculated the meshing frequency of helical gear by the formula, and verified the rationality of the equation by comparing with the measured meshing frequency.

Pfeiffer studied the vibration of gear transmission system by establishing the discrete model of gear system, and studied the model deeply by combining numerical simulation and physical experiment. When Singh, Xie and comparin studied the vibration problem of automobile transmission in neutral, a four degree of freedom nonlinear vibration model of gear was established, and the method of restraining gear knocking noise was studied in depth according to this model. At the same time, the change of knocking vibration noise in gear was analyzed when clutch, engine and torque changed. Pfeiffer and Kunert established a discrete percussion vibration model when they studied the conversion of deterministic model to stochastic model, and found that the knocking vibration has chaotic characteristics.

Padmanabhan and Singh, on the basis of previous studies, also use the four degree of freedom nonlinear model to further elaborate how to reduce the gear knocking noise and the influence of clutch, engine and torque variation on gear noise. According to the theory of multi-body dynamics, karagiannis and Pfeiffer established the knock model of gear pair and considered the condition of simulating impact. The model was calculated and analyzed by using the harmony algorithm. At the same time, the existence of chaos was further confirmed by Fokker Planck equation. Steven et al. Through modeling and analyzing the transmission gear transmission system in the dynamics software ADAMS, analyzed and predicted the knocking noise of the gear in the transmission system, and made an effective guidance for the related research of transmission gear noise.