Simplified models of turbine vibrations with breathing crack in the shaft
Two bar models of a transvesely cracked rotor are examined considering "breathing" of the slot. The first model is based on the elastic axis break due to crack. The other is based on the simple model of rotor line and simple, linear, binary model of the crack breathing mechanism. Strong non-linearities are introduced in the model of journal bearings, based on the theory of hydrodynamic lubrication. The paper presents the methodology of crack modeling, the algorithms of crack breathing mechanisms and calculations of shaft vibrations. The sample calculations were performed for models of a large power turbo-set.
Bibliogr. 15 poz., tab., wykr.
- Chasalevris A.C. and Papadopoulos C.A. (2006): Identification of multiple cracks in beams under bending. - Mechanical Systems and Signal Processing, vol.20, pp.1631-1673.
- Dimarogonas A.D. and Papadopoulos C.A. (1983): Vibration of cracked shafts in bending. - Journal of Sound and Vibration, vol.91, pp.583-593.
- Dimarogonas A.D. (1996): Vibration of cracked structures: A state of the art review. - Engineering Fracture Mechanics, vol.55, No.5, pp.831-857.
- Gomez-Mancilla J., Machorro-López J.M. and Nosov V.R. (2005): Crack Breathing Mechanisms in Rotor-Bearings Systems. Its Influence on System Response and Crack Detection. - ISCORMA-3 Conference, Cleveland, Ohio, USA, pp.202-211.
- Kicinski J. (2005): Assessment of materials and operational imperfections in rotating machinery. - Key Eng. Materials. - Trans. Tech. Publications, pp.391-400.
- Kiciński J. and Banaszek S. (2005): Crack indicators for large power turbo-set monitoring and diagnostic system. - Mechanics, vol.24, No.2, pp.77-81.
- Kicinski J. (2006): Rotor Dynamics. - Gdansk, Poland: The IFFM Publisher.
- Loutridis S., Douka E. and Hadjileontiadiset L.J. (2005): Forced vibration behaviour and crack detection of cracked beams using instantaneous frequency. - NDT&E International, vol.38, No.5, pp.411-419.
- Mayes I.W. and Davies W.G.R. (1994): Analysis of the response of a multi-rotor-bearing system containing a transverse crack in a rotor. - Trans. ASME J. Vib. Acoust. Stress Reliab. Des., vol.106, pp.139-145.
- Sekhar A.S., Mohanty A.R. and Prabhakar S. (2005): Vibrations of cracked rotor system: transverse crack versus slant crack. - Journal of Sound and Vibration, vol.279, pp.1203-1217.
- Shulzhenko N.G. (1987): Determination of the crack appearance symptom at the bending vibrations of weighty rotor. - Machine Engineering Problems, vol.27, pp.24-29 (in Russian).
- Shulzhenko N.G. (1992): The method of vibration spectrum determination of multi-supported rotor with transverse crack. - Machine Engineering Problems, vol.37, pp.10-15 (in Russian).
- Shulzhenko N.G. and Ovcharova G.B. (1997): The influence of elastic axis break of the transversely cracked rotor on its dynamic characteristics. - Problems of Reliability, No.4, pp.82-89 (in Russian).
- Wu. X., Friswell M.I., Sawicki J.T. and Baaklini G.Y. (2005): Finite element analysis of coupled lateral and torsional vibrations of a rotor with multiple cracks. - Proceedings of ASME Turbo Expo 2005 Gas Turbine Technology: Focus for the Future, Reno (NV), USA, vol.4, pp.841-850.
- Yang B. and Steve Suh C. (2006): On fault induced nonlinear rotary response and instability. - International Journal of Mechanical Sciences, vol.48, pp.1103-1125.