A Fault Analysis Cracked-Rotor-to-Stator Rub and Unbalance by Vibration Analysis Technique

Authors: B. X. Tchomeni, A. A. Alugongo, L. M. Masu

Abstract:

An analytical 4-DOF nonlinear model of a de Laval rotor-stator system based on Energy Principles has been used theoretically and experimentally to investigate fault symptoms in a rotating system. The faults, namely rotor-stator-rub, crack and unbalance are modeled as excitations on the rotor shaft. Mayes steering function is used to simulate the breathing behaviour of the crack. The fault analysis technique is based on waveform signal, orbits and Fast Fourier Transform (FFT) derived from simulated and real measured signals. Simulated and experimental results manifest considerable mutual resemblance of elliptic-shaped orbits and FFT for a same range of test data.

Keywords: A breathing crack, fault, FFT, nonlinear, orbit, rotorstator rub, vibration analysis.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1109337

References:

[1] T. H. Patel, and A. K. Darpe, Coupled bending torsional vibration analysis of rotor with rub and crack, Journal of Sound and Vibration Vol. 326, 2009, pp 740–752.
[2] F. Chu, and W. Lu, Determination of the rubbing location in a multi-disc rotor system by means of dynamic stiffness identification. Journal of sound and vibration, 2001. 235-246.
[3] R. F. Beatty, Differentiating Rotor response due to radial rubbing, Journal of Vibration, Acoustics, Stress, and Reliability in Design Vol107, 1985, pp151–160.
[4] B. O. Al-bedoor, Transient torsional and lateral vibrations of unbalanced rotors with rotor-to-stator rubbing. Journal of Sound and vibration 229(3), 2000, 627-645.
[5] J. T. Sawicki, J. Padovan, and R. Al-Khatib, The Dynamics of Rotor with Rubbing. International Journal of Rotating Machinery 1999, Vol. 5, No. 4, 1998, pp. 295-304.
[6] J. T. Sawicki, X. Wu, G. Y. Baaklini, and A. L. Gyekenyesi, “Vibrationbased crack diagnosis in rotating shafts during acceleration through resonance,” in Nondestructive Evaluation and Health Monitoring of Aerospace Materials and Composites II, vol. 5046 of Proceedings of SPIE, 2003, pp. 1–10, San Diego, Calif, USA.
[7] Y. B. Kim, and S. T. Noah, Bifurcation analysis for modified Jeffcott rotor with bearing clearances, Nonlinear Dynamics Vol. 1, 1990, pp 221-241.
[8] F. Chu, and W. Lu, Stiffening effect of the rotor during the rotor-tostator rub in a rotating machine, Journal of Sound and Vibration Vol. 308, 2007, pp 758–766.
[9] R. Sukkar, and A. S. Yigit, Analysis of fully coupled torsional and lateral vibrations of unbalanced rotors subject to axial loads. Kuwait J. Sci. Eng. 35 (2B), 2008, pp. 143-170.
[10] R. Gasch, A Survey of the Dynamic Behaviour of a Simple Rotating Shaft with Transverse Crack, Journal of Sound and Vibration, 1993, 160(2): 313-332.
[11] B. Grabowski, The vibrational behavior of a turbine rotor containing a transverse crack. ASME Design Engineering Technology Conference, St. Louis, 1979. Paper No. 79-DET-67.
[12] J. J. Sinou, Condition Monitoring for Notched Rotors Through Transient Signals and Wavelet Transform Experimental Mechanics 49 (2012) 683- 695.
[13] I. Mayes, and W. Davies, The vibration behavior of a rotating shaft system containing a transverse crack. Vibration in rotating machinery, Inst. Mech, E. 1976, p.53-65.
[14] B. X. Tchomeni, A. A. Alugongo, and L. M. Masu, In situ Modelling of Lateral-Torsional Vibration of a Rotor-Stator with Multiple Parametric Excitations. World Academy of Science, Engineering and Technology International Journal of Mechanical, Aerospace, Industrial and Mechatronics Engineering Vol:8 No:11, 2014.
[15] A. S. Yigit, and A. P. Christoforou, Coupled Torsional and Bending Vibrations of Actively Controlled Drillstings. Journal of Sound and Vibration, 2000, 234: 67-83.
[16] A, D. Dimarogonas, Vibration Engineering, West Publishers, St. Paul. 1976.
[17] A. K. Darpe, Dynamics of cracked rotor. PhD Thesis, IIT Delhi, 2000.