Experimental Dynamic Analysis of a Breathing Cracked Rotor

• Published in: Chinese journal of mechanical engineering 2017-09, Vol.30 (5), p.1177-1183
• Main Authors: Guo, Chao-Zhong, Yan, Ji-Hong, Bergman, Lawrence A.
• Format: Article
• Language: English
• Subjects: Bending fatigue; Breathing; Coasting; Crack propagation; Dynamic response; Electrical Machines and Networks; Electronics and Microelectronics; Engineering; Engineering Thermodynamics; Frequency spectrum; Heat and Mass Transfer; Instrumentation; Machines; Manufacturing; Mechanical Engineering; Orbits; Original Article; Power Electronics; Processes; Rotating machinery; Rotation; Signal processing; Spectra; Theoretical and Applied Mechanics; 临界转速; 动力学分析; 呼吸; 实验; 工业机械; 旋转机械; 裂纹转子; 轨道演化
• ISSN: 1000-9345; 2192-8258
• DOI: 10.1007/s10033-017-0180-7

Crack fault diagnostics plays a critical role for rotating machinery in the traditional and Industry 4.0 fac- tory. In this paper, an experiment is set up to study the dynamic response of a rotor with a breathing crack as it passes through its 1/2, 1/3, 1/4 and 1/5 subcritical speeds. A cracked shaft is made by applying fatigue loads through a three-point bending apparatus and then placed in a rotor testbed. The vibration signals of the testbed during the coasting-up process are collected. Whirl orbit evolution at these subcritical speed zones is analyzed. The Fourier spectra obtained by FFF are used to investigate the internal frequencies corresponding to the typical orbit characteris- tics. The results show that the appearance of the inner loops and orientation change of whirl orbits in the experiment are agreed well with the theoretical results obtained previously. The presence of higher frequencies 2X, 3X, 4X and 5X in Fourier spectra reveals the causes of subharmonic reso- nances at these subcritical speed zones. The experimental investigation is more systematic and thorough than previ- ously reported in the literature. The unique dynamic behavior of the orbits and frequency spectra are feasible features for practical crack diagnosis. This paper provides a critical technology support for the self-aware health man- agement of rotating machinery in the Industry 4.0 factory.