Study of the diagnostic features of a rotor with a transverse crack

With the aim of seeking the diagnostic features of a rotor crack, the dynamic responses of a cracked rotor in the subcritical, trans-critical and super-critical regions of operation are investigated in this paper, based on the analysis of the vibration signatures collected during the acceleration process. A few feasible methods based on the holo-spectral analysis technique are specially developed for investigating the transient vibration behaviour of a cracked rotor in a more detailed way. The experimental results show that, because the proposed methods provide much more detailed and distinguishable characteristics for diagnosis, they are really effective for capturing incipient transverse cracks in a rotor. Moreover, these methods are also generic and applicable to all high-speed rotating machines such as turbines, generators, motors and pumps. In addition, the crack breathing behaviour in the super-critical region is further investigated by experiments, from which a new research subject is brought forward. This is very helpful for correctly understanding the vibration characteristics of a cracked rotor. The research work in this paper makes a marked contribution for the detection of the incipient crack and has important significance for obviating catastrophic machine failures.