Date of Award


Degree Type



Mechanical Engineering

First Advisor

Sawicki, Jerzy

Subject Headings

Rotors -- Dynamics, Turbomachines, Magnetic bearings, Impellers, Rotordynamics, Turbomachinery, Active magnetic bearings, Health monitoring, Shaft crack, Cracked rotor, Breathing crack, Magnetic actuator, External excitation, Transverse rotor crack


Cracked rotors present a significant safety and loss hazard in nearly every application of modern turbomachinery. This thesis focuses on the health monitoring, modeling, and analysis of machines with transverse breathing cracks, which open and close due to the self-weight of the rotor. After considering the modeling of cracked rotors, the thesis investigates an active structural health monitoring approach, focusing on the application of an active magnetic actuator to apply a specially designed external force excitation to the rotating shaft. Extensive experimental data has been collected and analyzed utilizing advanced diagnostic techniques. The presented results demonstrate that the use of a magnetic force actuator to apply external excitation has potential in the diagnostics of cracked rotors. The observed unique crack signatures demonstrate the ability of the method for early diagnosis of transverse rotor cracks