Sideband Frequency Response Function Based Damage Identification of Rotor System with Open Cracks

This paper develops a new vibration based damage detection method to identify the location and severity of structural damage of periodically time-varying systems. The frequency response function (FRF) shifts induced by cracks are utilized to detect the location, depth and orientation angle of open transverse cracks on a shaft-disk system. The dynamical model of system is built based on the Lagrange principle and the assumed mode method while the crack model for periodically time-varying systems is based on the fracture mechanics. This method provides the advantages of arbitrary interrogation frequency and multiple inputs/outputs which greatly enriches the dataset for damage identification. The method is synthesized via harmonic balance and numerical examples for a shaft/disk system to demonstrate the effectiveness in detecting both location and severity of the structural damage.