Abstract
This paper intends to extend the application of the residual operational deflection shape (R-ODS) to a simplified model of the LP turbine of a steam turbo generator. The numerical model consists of a stepped shaft which accommodates some balance disks to represent the blades at different stages of the LP turbine. The ability of the R-ODS method in detecting cracks in beam-like structures has already been presented. The method removes the effect of the first harmonic component (1x) from the ODSs at higher harmonic components to highlight the non-linear behaviour of cracks. In this paper, single and multiple cracks are introduced at different locations to the finite element model of the rotor. It is assumed the rotor can be taken out from the rig and mounted on a simply supported boundary condition. After carrying out the modal analysis, the rotor is excited at its first resonant frequency and acceleration responses along the rotor are computed to construct the ODSs. The R-ODS method uses the normalised ODSs for the purpose of crack detection. The curvature of R-ODS method is also presented for further improvement in indication of crack locations especially for multiple-crack rotors.
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Asnaashari, E., Sinha, J.K. (2015). Off-Line Crack Detection in Rotors. In: Sinha, J. (eds) Vibration Engineering and Technology of Machinery. Mechanisms and Machine Science, vol 23. Springer, Cham. https://doi.org/10.1007/978-3-319-09918-7_10
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DOI: https://doi.org/10.1007/978-3-319-09918-7_10
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