Gear transmission system dynamics mainly studies the mechanical behavior of gear transmission motion and power process, including research on dynamic excitation, establishment and solution of system model, research on dynamic response of system, etc, It can be divided into positive problem and inverse problem according to its properties: the forward problem is to study the dynamic response of the system under known conditions, including the determination and description of dynamic excitation and system model, and the solution of response, which is the main research content of gear system dynamics; the inverse problem is to carry out load identification, fault diagnosis, model modification and improvement when the system response is known, It mainly focuses on fault diagnosis. So far, gear transmission system dynamics has formed a relatively complete theoretical system.

Gear transmission system is a complex nonlinear dynamic system. The key task of gear dynamics analysis is to establish the dynamic model of gear transmission system. At present, the main methods to establish the dynamic model of gear transmission system are: lumped parameter method, transfer matrix method and finite element method. The lumped parameter method, also known as the lumped parameter method, concentrates the mass distributed in a continuous structure at a point and turns it into several lumped masses. The masses are connected by springs. These springs have only elasticity but no mass, thus forming a relatively simple and intuitive limited degree of freedom system.

This method is simple in structure, easy to understand, easy to establish equations, and easy to solve. However, the degree of freedom of this model is relatively small, which is different from the actual structure of the system, and the accuracy of the model is relatively poor. The transfer matrix method is to deal with the system in sections and connect its head and tail by establishing the transfer matrix, so as to obtain the expression relationship of the whole system. The requirement of this method for computer is relatively simple, and the calculation time is short. However, when calculating the high-order frequency or the rotor system is relatively large, the calculation accuracy is relatively low, and it is easy to produce numerical instability and “root leakage” phenomenon. In the analysis of complex model, it can not accurately carry out the coupling analysis between subsystems. In recent years, with the rapid development of computer technology, the application of finite element method in engineering field has been paid more and more attention by scholars at home and abroad.