Abstract: Model based fault identification techniques can be used to diagnose local faults in rotating machinery; The equivalent loads that represent fault forces can be used to identify the fault location. But in some cases the equivalent loads smeare over many nodes in using this method, and make it hard to identify accurate fault location and transient fault force. The fault location is identified using least squares fitting approach by the system’s vibration shape when the fault signal is periodic or quasi-periodic. And after the fault location is ascertained, the transient fault forces can be identified by transient residual vibration using simple matrix multiplications and additions. The fault force location and magnitude of the rotor system can be detected precisely by using only a few sensors. Numerical simulations on rotor to stator rub and experiment in testrig are used to test the method, which can prove the efficiency of the method.

Key words: Diagnosis, Local fault, Model based, Rotating machinery