Detection of Cracks in Shafts via Analysis of Vibrations and Orbital Paths

##plugins.themes.bootstrap3.article.main##

##plugins.themes.bootstrap3.article.sidebar##

R. Peretz L. Rogel J. Bortman R. Klein

Abstract

Shafts are often subjected to difficult operating conditions in high-performance rotating equipment such as compressors, steam and gas turbines, generators and pumps. As a result, shafts are susceptible to fatigue failures due to transverse cracks. In this study, vibration monitoring and orbital paths observation were used to detect the presence of a flaw in a shaft. Two types of flaws were tested: a straight slot, and a fatigue crack. For both flaw types, specimens of different depths were examined in order to assess the detection capability. A new approach to examine vibrations at the critical speed is proposed; this speed is chosen because of the strong connection to the basics of the physical problem. Orbital paths are suggested as means for fault detection as well. The presence of a straight slot in the shaft was found to be related to a decrease in the natural frequency and to a decrease in amplitude of the first order at critical speed. For the fatigue crack, a consistent trend in critical speed and in amplitude was not seen as crack depth grew. A new method to detect the change in the shaft natural frequency is proposed. The combination of two indicators, change in critical speed and change in amplitude at critical speed, are suggested for classification of flaw size. For the straight slot case, the method proposed was able to distinguish between different fault depths.

How to Cite

Peretz, R., Rogel, L., Bortman, J., & Klein, R. (2016). Detection of Cracks in Shafts via Analysis of Vibrations and Orbital Paths. Annual Conference of the PHM Society, 8(1). https://doi.org/10.36001/phmconf.2016.v8i1.2552
Abstract 21 | PDF Downloads 28

##plugins.themes.bootstrap3.article.details##

Keywords

PHM

References
AL-Shudeifat, M. A., Butcher, E. A., & Stern, C. R. (2010). General harmonic balance solution of a cracked rotorbearing-disk system for harmonic and sub-harmonic analysis: Analytical and experimental approach. International Journal of Engineering Science, 48(10), 921-935. doi:10.1016/j.ijengsci.2010.05.012
Budynas, R. G., & Nisbett, J. K. (2011). Shigley's mechanical engineering design: Ninth edition. New York, NY: McGraw-Hill.
Dimarogonas, A. D. (1996). Vibration of cracked structures: a state of the art review. Engineering fracture mechanics, 55(5), 831-857.
Gudmundson, P. (1983). The dynamic behaviour of slender structures with cross-sectional cracks. Journal of the Mechanics and Physics of Solids, 31(4), 329-345. doi:10.1016/0022-5096(83)90003-0
Kunche, S., & Ganeriwala, S. N. S (2013). The Effect of Unbalance and Misalignment on Detection of Rotor/Shaft Cracks Using Vibration Analysis. The
Tenth International Conference on Condition Monitoring and Machinery Failure Prevention Technologies, June 18-20, Kraków, Poland.
Machorro-López, J. M., Adams, D. E., Gómez-Mancilla, J. C., & Gul, K. A. (2009). Identification of damaged shafts using active sensing—simulation and
experimentation. Journal of Sound and Vibration, 327(3), 368-390. doi:10.1016/j.jsv.2009.06.025
Sabnavis, G., Kirk, R. G., Kasarda, M., & Quinn, D. (2004). Cracked shaft detection and diagnostics: A literature review. Shock and Vibration Digest, 36(4), 287. doi:10.1177/0583102404045439
Sinou, J. J., & Lees, A. W. (2007). A non-linear study of a cracked rotor. European Journal of Mechanics-A/Solids, 26(1), 152-170. doi:10.1016/j.euromechsol.2006.04.002
Sinou, J. J. (2008). Detection of cracks in rotor based on the 2× and 3× super-harmonic frequency components and the crack–unbalance interactions. Communications in Nonlinear Science and Numerical Simulation, 13(9), 2024-2040. doi:10.1016/j.cnsns.2007.04.008
Suryawanshi, V. J., & Dhamande, L. S. (2014). Vibration Based Condition Assessment of Rotating cracked shaft using changes in critical speed and RMS Velocity response functions. International Journal of Current Engineering and Technology, Special Issue-3.
Varney, P., & Green, I. (2012). Crack detection in a rotor dynamic system by vibration monitoring—Part II: Extended analysis and experimental results. Journal of Engineering for Gas Turbines and Power, 134(11), 112501. doi:10.1115/1.4007275
Wauer, J. (1990). On the dynamics of cracked rotors: a literature survey. Applied Mechanics Reviews, 43(1), 13-17.
Section
Technical Papers