Abstract
Continuous operation of rotating machinery with a rotor crack is a risk condition since the rotor crack grows rapidly and may fail causing a catastrophic accident. This paper investigates the estimation of both the depth and position of the rotor crack by utilizing the natural frequency of the rotor system with a breathing crack. First, by using the finite element method, the dynamic responses of a cracked rotor system under applying periodical external excitation are investigated. The natural frequency of the case with breathing crack is calculated by using that of the case with open crack. From the obtained natural frequency, the occurrence frequency of the sub-resonance due to crack is calculated for various values of depth and position of the crack. The estimation method of both the depth and position of the breathing crack is proposed, and it is validated by the numerical simulation.
