Dynamic Characteristics Analysis of Rotor-crack-loose Coupling Fault of Engine Rotor System

The nonlinear dynamic model of the double-span rotor system under the rolling bearing bearing is established. The fourth-order-five-step fixed-step Runge-Kutta method is used to analyze the nonlinear dynamic model. The dynamic responses of the rotor with the change of the speed under the five conditions of no fault, rubbing fault, crack fault, one end loose fault and rubbing-crack-loose coupling fault are compared respectively. The effects of rotor unbalance, rubbing stiffness and loose bearing housing quality on system response under rubbing-crack-loose coupling failure conditions are numerically analyzed. The results show that when the system has a rubbing fault, the first-order critical speed is increased slightly and the dynamic behavior is more complicated; when there is a crack fault, the first-order critical speed is reduced; when there is a loose fault, the response chaotic area becomes larger; when there are three kinds of coupling faults, the super first-order critical speed response appears large-area chaos; with the increase of rotor unbalance and rubbing stiffness, the response tends to chaos, and the quality of the loose end bearing seat is sensitive at high speed.