Abstract
Rod fastened rotor is widely used in gas turbine, aero engine, and other occasions. The bending stiffness of the contact interface directly affects the stable operation of the rotor. Dynamic model of the rod fastened rotor-bearing system has been established considering nonuniform stiffness of interface. The motion equation of this system has been deduced from Lagrange’s equations. The linear dynamic characteristics of this rotor has been investigated, such as Campbell diagram, critical speed, and formation, and the nonlinear characteristics of this system, such as chaos and bifurcation, has been investigated too. The result shows that “bistable state” characteristic appeared on the rod fastened rotor system; that is, there are two critical speeds for each order, and they are all positive precession critical speed, and the amplitude response to the lower critical speed is much larger than that its counterparts to the higher critical speed. In terms of nonlinear characteristics, the rod fastened bearing system has experienced periodic 1 motion, multiple periodic motion, quasi-periodic motion, periodic 1 motion, and chaotic motion successively.
Highlights
Rod fastened rotor is widely used in gas turbine, aero engine, and other occasions. e bending stiffness of the contact interface directly affects the stable operation of the rotor
The first- to third-order critical speed of this system is 470.63 rad/s, 1223.06 rad/s, and 2022.56 rad/s, respectively, as shown in Figure 6. e nonlinear dynamic behaviors of the rod fastened rotor-bearing system are performed by using the fourth-order Runge–Kutta method and implemented in MATLAB
Based on Lagrange’s equation, the model of rod fastened rotor-bearing system under the condition of nonuniform bending stiffness of interface has been established in this paper. e linear dynamics behaviors have been explored, such as Campbell diagram and critical speed. e nonlinear dynamics behaviors have been studied by using the fourthorder Runge–Kutta method. e bifurcation diagram, vibration waveform, spectrum, phase trajectory, and Poincare map are given to illustrate the nonlinear dynamic phenomena of the system. e following conclusions can be drawn from the above research
Summary
Rod fastened rotor is widely used in gas turbine, aero engine, and other occasions. e bending stiffness of the contact interface directly affects the stable operation of the rotor. Dynamic model of the rod fastened rotor-bearing system has been established considering nonuniform stiffness of interface. In order to prevent mechanical unstable operation, it is necessary to study the stability and nonlinear characteristics of rotor-bearing system. Wang [2] established the dynamic model of rub-impact rotor system and studied the periodic response stability of the system by Floquet theory. Gardner et al [3] analyzed the nonlinear motion of the rotor system under the long bearing after linear instability and studied the subcritical and supercritical bifurcation in the method of multiscale. Bonello et al [4] studied the nonlinear dynamic response of an extruded oil film damper-rotor system by harmonic balance method. E rod fastened rotor-bearing system is widely used in gas turbines and aeroengines (see Figure 1). Hei et al [8]
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