Dynamic response analysis of rotor-bearing systems with cracked shaft

A general dynamic model for a large-scale rotor-bearing system with a cracked shaft is introduced. A finite shaft element with a crack is developed using a consistent finite element approach. The model accommodates shafts with tapered portions, multiple disks and anisotropic bearings. The formulation is applicable to rotor-bearing systems with different practical design configurations including intermediate bearings, shaft overhang. and stepped shaft assemblies. A reduced order form of equations of motion is obtained by invoking the actual non-planar (complex) modal transformations. The time-response due to different excitations are calculated, and comparisons are presented to establish the validity and efficiency of the reduced order model. It is hoped that the developed computational scheme offers an efficient and essential core module in establishing other specialized crack detection schemes for rotor-bearing systems.