Abstract
This work aims to diagnose the crack size of a nonlinear rotating shaft system based on the qualitative change of the system oscillatory characteristics. The considered system is modeled as a two-degree-of-freedom horizontally supported nonlinear Jeffcott rotor system. The influence of the crack size on the system whirling motion for the primary, superharmonic, and subharmonic resonance cases are investigated utilizing the bifurcation diagram, Poincaré map, frequency spectrum, and whirling orbit. The obtained numerical results revealed that the cracked system whirling motion is subjected to a continuous qualitative change as the crack size increases for the superharmonic resonance case, where the system can exhibit period-1, period-2, quasi-periodic, period-3, period-doubling, chaotic, and period-2 motions, sequentially. In addition, an asymmetry is observed in the system whirling orbit due to both the shaft weight and shaft crack. Moreover, it is found that the disk eccentricity does not affect the nature of these motions. Accordingly, we illustrated a simple method to diagnose the existence of such a crack and to quantify its size via monitoring the system lateral vibrations at the superharmonic resonance. Finally, all the obtained numerical results are concluded and a comparison with already published work is included.
Highlights
Rotating machines cover a wide range of engineering applications that provide the backbone of numerous industries such as steam turbines, generators, gas turbines, aerospace, pumps, turbomachinery, automobile engines, high-speed compressors etc
Many research papers have been dedicated to analyze and investigate the rotating machinery nonlinear vibrations, where Ganesan [1] investigated the effect of the bearing clearance asymmetry on stability of the Jeffcott rotor system
The authors modeled their system as a simple Jeffcott rotor system, where the 1:2 and 1:3 superharmonic resonance cases were investigated
Summary
Rotating machines cover a wide range of engineering applications that provide the backbone of numerous industries such as steam turbines, generators, gas turbines, aerospace, pumps, turbomachinery, automobile engines, high-speed compressors etc. Dai and Chen [35] explored the dynamic stability of a cracked shaft having asymmetric support They applied the incremental harmonic balance method to investigate the proposed model, where the shaft nonlinear stiffness coefficient, the shaft mass, and the disk mass were included in the studied model. Hou et al [44] studied dynamical behaviors of a cracked aircraft rotor when subjected to the maneuvering load The authors modeled their system as a simple Jeffcott rotor system, where the 1:2 and 1:3 superharmonic resonance cases were investigated. Saeed and Eissa [46] studied the case of lateral vibrations of a nonlinear horizontally supported Jeffcott rotor system having a shaft with a transverse crack at the primary resonance. The obtained results may not be applicable in the case of complicated rotor models, where many system parameters such as the bearings clearance, and the varying loads may affect the system dynamics [52]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
