Research on the characteristics of variable parameters in nonlinear cracked rotor system with rub-impact faults

The dynamic characteristics and its early detection are the most important tasks in cracked rotor system. It is difficult to accurately estimate the crack. And the vibration will be severe in its rapid rise. So there maybe happen the rubbing faults between the shaft and the bearings. An analytic model has been set up to investigate the crack and rubbing coupling faults. The nonlinear dynamic characteristics of the system can be simulated. Especially, the effects of the variable parameters, such as the crack parameter, the rub parameter and the bearing parameter, are analyzed respectively. The results show that the effects of crack and rub-impact are not their linear summation but their coupling. The rotor system also becomes more complex and the effects of the three nonlinear factors are different. And the effects of crack and rub-impact parameters are more serious. To detect and diagnose a practical cracked rotor system, the probability of rub-impact must be taken into account. A reasonable nonlinear dynamic model should be set up, which must consider the coupling of the crack and the rub-impact. And more attention should be paid to the effect of the crack parameter and the rubbing parameter, not to the baring parameter in the rotor system.