Chaotic Behavior Analysis and Control of Rotor-Oil Film Bearing Systems

• Main Authors: Her-terng Yau, 姚賀騰
• Other Authors: Cha''o-Kuang Chen
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/70978586748130679700

博士 === 國立成功大學 === 機械工程學系 === 88 === For the control of chaotic system, a sliding mode hyperplane design for a class of chaotic systems with disturbances and uncertainties is considered in this thesis. The concept of extended systems is used such that continuous control input is obtained using a sliding mode design scheme. It is guaranteed that under the proposed control law, chaotic systems can asymptotically track target orbits. Assigning the corresponding dynamics of the sliding surfaces can arbitrarily set the converging speed of error states. Illustrative examples of controlled Duffing-Holmes system and Lorenz system are presented. For the analysis of chaotic system, the bifurcation and chaos of the unbalance response of bearings-rotor system with nonlinear suspension are investigated based on the assumption of an incompressible lubricant together with the short bearing approximation. Numerical results show that due to the nonlinear factors, the trajectory of the journal center demonstrates steady state symmetric motion even when the trajectory of the bearing center is in a state of disorder. The unidirectional bifurcation phenomena of the bearing center are detected, which is unique for the non-linear dynamical systems. The phenomena showed that the bearing center is in the state of chaotic motion in only one direction at the unidirectional motion, however, the journal center is in a state of 2T-periodic motion. For the control of rotor-bearing system, the hybrid squeeze-film damper bearing with active control is proposed in this study. The pressure distribution and the dynamics of a rigid rotor supported by such bearing are studied. A PD controller is used to stabilize the rotor-bearing system. Numerical results find that the rotor center exist sub-harmonic, quasi-periodic and chaotic vibration. In order to avoid the non-synchronous vibrations, an increased proportional gain is applied to control this system. It is shown that the non-synchronous rotor motion becomes synchronous motion under control action.