Vibration analysis of a cracked rotor using Hilbert–Huang transform

In this paper, the startup transient response of a rotor with a propagating transverse crack is investigated using Hilbert–Huang Transform (HHT)—a relative novel time-frequency analysis method. The rotor with a growth crack is modeled by finite element method (FEM) and Dimarogonas’ method. The influence of crack propagating ratio (CGR) on instantaneous response of the rotor as it passes through the critical speed and sub-harmonic resonances is analyzed. The 1X (one times rotating frequency), 2X (two times rotating frequency) and 3X (three times rotating frequency) vibration components are studied when they appear, reach its peak and decay during startup process. Some conclusions are achieved which may be useful to detect transverse crack on the shaft. It demonstrates that the HHT is an effective tool for the analysis of non-linear, unsteady transient vibration response.