Modified breathing mechanism model and phase waterfall plot diagnostic method for cracked rotors

Transverse breathing cracks are a primary damage mode in rotor systems and seriously influence the safety and reliability of equipment operation. The vibration characteristics exhibited by cracked rotors when passing through critical speeds serve as important evidence in the diagnosis of cracks, and a breathing mechanism model without weight dominance is needed to study these resonant characteristics. In this work, a restoring force modified model is proposed for studying the breathing mechanism of cracked Jeffcott rotors without weight dominance. Furthermore, a novel phase waterfall plot method that can identify frequency components with weak amplitudes is proposed to analyze the vibration response characteristics of cracked Jeffcott rotors. Numerical and experimental studies indicate that the phase waterfall plots effectively recognize the weak characteristic frequencies of cracked rotors. This study can also provide references for the crack monitoring of rotor systems.