| The popularity of high-speed trains is becoming the development tendency of contemporary rail transportation. The safety is vitally significant in the study of high-speed trains. The safety and stability of gear transmission system is a key factor to reduce the accidents. The study on rotor dynamics and the dynamics simulation of gear transmission system are the most important parts of transmission gear box design.Based on the theory of rotor dynamics, the dynamic characteristics of gear and rotor-bearing system of transmission gear box is researched both under coupling and decoupling conditions by MATLAB, which makes informative suggestions on the stability of high-speed trains. Dynamic simulations are performed to study the flexible models of gear system based on virtual prototyping technology, and furthermore, the data can be used to study gear strength, stiffness, and fatigue life.What the dissertation has mainly done is as follows:1. The traditional transfer matrix method and Riccati transfer matrix method are introduced. Frequency characteristic equations of rotor system critical speed are obtained by two methods. The reason of choosing Riccati transfer matrix method is explained.2. The lumped mass, the lumped rotational inertia, the stiffness of the oil film, the mass and stiffness of bearing seat are calculated. Also, Uniaxial Riccati transfer matrix is listed without considering gear coupling and the computation program based on MATLAB is created. Different orders of critical speeds of high-speed shaft and low-speed shaft are figured out. Moreover, the mode diagrams of vibration and bending moment diagrams of uniaxial rotor at various critical speeds are obtained. Uniaxial vibration is analyzed without considering gear coupling.3. The whole transmission matrix method for coupled bending-torsional vibration analysis of multi-rotor system with gear coupling is studied and specific computing method of the helical gear coupling matrix is explained.4. The model of gear and bearing rotor system of transmission gear box of high-speed trains is simplified, the transfer matrix of each section is listed, and the whole transmission matrix is calculated as well. Frequency characteristic equations of system under coupled bending-torsional vibration condition are obtained with Riccati transformation and the computation program based on MATLAB is created. Different orders of critical speeds of output shaft (the low-speed shaft) are figured out, and both of lateral and vertical mode diagrams of vibration and bending moment diagrams at certain various critical speeds are finally obtained.5. The flexible models of gear system, the meshing strength curves, and their maximum and average values of the meshing strength under specific conditions have been obtained with the help of Pro/E, ANSYS, and ADAMS software. |
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