Journal of Sound and Vibration
Cracked rotors are not only important from a practical and economic viewpoint, they also exhibit interesting dynamics. This paper investigates the modelling and analysis of machines with breathing cracks, which open and close due to the self-weight of the rotor, producing a parametric excitation. After reviewing the modelling of cracked rotors, the paper analyses the use of auxiliary excitation of the shaft, often implemented using active magnetic bearings to detect cracks. Applying a sinusoidal excitation generates response frequencies that are combinations of the rotor spin speed and excitation frequency. Previously this system was analysed using multiple scales analysis; this paper suggests an alternative approach based on the harmonic balance method, and validates this approach using simulated and experimental results. Consideration is also given to some issues to enable this approach to become a robust condition monitoring technique for cracked shafts.
Jerzy T. Sawicki, Michael I. Friswell, Zbigniew Kulesza, Adam Wroblewski, John D. Lekki. (2011). Detecting cracked rotors using auxiliary harmonic excitation. Journal of Sound and Vibration, 330(7), 1365-1381, doi: dx.doi.org/10.1016/j.jsv.2010.10.006.
NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Sound and Vibration. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Sound and Vibration, 330, 7, (03-28-2011); dx.doi.org/10.1016/j.jsv.2010.10.006