The gear shaft of the transmission system is one of the most important components of power transmission in the complex power equipment. Its main function is to support the rotating parts in the rotating machinery and to transmit the movement, torque or bending moment. The gear transmission system mainly bears the alternating load of the gear end in the gear assembly. Due to the periodic change of gear engagement force, the torsional vibration of the gear shaft is produced, which leads to the adhesion sliding friction instability between the gear shaft shoulder and the bearing inner ring. With the continuous operation of the gear transmission system, fretting wear of the gear shaft shoulder is caused as shown in Fig. 1.2. Fretting wear of gear shoulder is an important part of gear transmission wear. Severe gear shoulder wear may cause fatigue fracture of gear shaft, cause serious mechanical failure and shorten the working life of complex power equipment. Therefore, the research on Fretting Wear Mechanism of gear shoulder has certain practical application value.

In recent years, many enterprises and scientific research institutions have conducted in-depth research on the mechanism of torsional vibration of many kinds of rotating machinery, and provided abundant experimental data. These results are helpful to analyze the causes of torsional vibration of rotating machinery from a qualitative point of view.

However, there are few reports on the deep mechanism of fretting wear of gear shaft under the complex conditions of high transmission power, high energy density and variable speed. How to effectively solve the problem of fretting wear of gear shaft under the complex working conditions of high transmission power, high energy density and variable rotation speed has always been a research problem in the field of friction and wear at home and abroad. Therefore, this paper is based on the deep analysis of the torsional vibration mechanism of the gear shaft under the complex conditions of high transmission power, high energy density and variable rotation speed, and the research and analysis of the stick slip effect caused by the friction between the gear shoulder and the inner ring of the bearing, as well as the torsional effect of the gear shoulder induced by the nonlinear structural stiffness and damping of the gear shaft In this paper, the nonlinear torsional vibration model and fretting wear model of the rotating machinery gear shoulder are put forward, which can enrich the research results of the vibration mechanism and fretting wear mechanism of the rotating machinery effectively, reveal the torsional vibration friction mechanism of the rotating machinery gear shoulder and the causes of fretting wear, so as to promote the development of the vibration theory and fretting wear theory of the rotating machinery The calculation and control of torsional instability vibration and fretting wear of rotating machinery provide reasonable theoretical analysis and experimental verification.