Research Of Crack Rotor Vibration Control And Delaying Crack Propagation

Rotor system is an important part of the high-power and high rotation speed motive power machines such as aero-engine, steam turbine, generator sets, heavy duty machine, etc,which usually works under the action of high temperatures, high presses and strong loads. The micro material defects and micro machining damages from the rotor can induce the crack propagation, and this kind of crack can cause the catastrophic accidents. Therefore, the research of previous crack monitoring and detecting is significant, vibration control and delaying crack propagation is critical for military, aerospace and meeting an emergency. It is also important for preventing catastrophic accidents and improving economic benefits.Based on the domestic and overseas research techniques of the cracked rotor,two-degree-of-freedom dynamic model of the nonlinear cracked rotor, Electro-Magnetic Actuator(EMA) model and the describing function of crack breathing have been built and the parameter self adjustable Fuzzy-PID controller has been designed. The main content and conclusions of the paper are shown below. First, the vibration characteristics of the system,the crack breathing state and the crack breathing period are investigated in different parameters of the synchronous state through the numerical simulation. In addition, the crack breathing state is also investigated in the asynchronous state. In this paper, it proposed a novel method of the delaying crack propagation using the EMA in order to realize the vibration control and delaying crack extension. Finally, the traditional PID controller and Fuzzy-PID controller have been used to control the nonlinear rotor system with the EMA control. Then,we compared the advantages and disadvantages of the two control strategies. By comparing the different parameters(rotational speed, crack angle, crack depth and nonlinear parameters,etc.) influences on crack breathing state, the mutation laws of the crack breathing state are summarized in the synchronous and asynchronous to verify the feasibility of delaying the crack extension mechanism. Comparing with the traditional PID control, Fuzzy-PID control has outstanding advantages.The results showed that the EMA can realize the vibration control of the cracked rotor in the sub-critical speed, critical speed and super-critical speed, and the goal of delaying crack extension also can be reached during the working process of the cracked rotor. Fuzzy-PID control has smaller displacement response and shortly setting time to compare with traditional PID control. The results shown Fuzzy-PID control has strong robustness and anti interference ability.