Study On Bending-Torsion Vibration Of Geared Dual-Rotors

With the progress of modern industry, the rotating machinery develops towards the direction of high-speed and high-power, so that the vibration of rotor becomes more important. Gear drive is the most widely used in the transmission of rotating machinery, therefore, it is necessary to carry out in-depth study on dynamics characteristic of geared rotor system.In this paper, while the bending-torsion5-DOF are taken into consideration, the finite element method and MATLAB software are used to derive axis unit, disk unit, and bearing unit equations of motion. By introduction of the single rotor system overall mass, stiffness, damping matrix formation rule, this paper obtains the overall5-DOF motion equation of single rotor system. Through analysis and reduction of the homogeneous motion equation of single rotor system, the author gets the eigenvalues and eigenvectors and extracts the corresponding critical speeds and mode shapes. And calculating the single rotor system bending and torsion vibration unbalance response. Based on force and torque balance and simplified analysis, a gear pair unit finite element model of bending and torsion is established, and the gear mesh stiffness and damping formula is given. By coordinate transformation, the gear pair unit motion equation under generalized coordinate is obtained, then the different superposed matrix laws of two gears’node number adjacent and non-adjacent is introduced. And composing of non-coupled gear-rotor motion equation and gear pair unit motion equation, the author gets coupled gear-rotor motion equation and calculates critical speeds, vibration modes, bending and torsion vibration unbalance responses of non-coupled and coupled gear-rotor systems. At last the author studies the influence of gear mesh stiffness, gear radio and bearing stiffness on the natural frequency of gear-rotor system.