PSI - Issue 39

Nabam Teyi et al. / Procedia Structural Integrity 39 (2022) 333–346 Author name / Structural Integrity Procedia 00 (2019) 000–000

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1. Introduction A rotor is an essential component of nearly all mechanical systems. A rotor unit is a shaft that is supported by bearings and has a flange, a disc, or a gear running down its axis. There could be multiple discs or other items mounted to the shaft. A rotating shaft (a rotor) might be regarded the heart of any machine system because practically all machine systems involve some motion transmission from linear to rotary or vice versa. Rotor behaviour can be found in turbo machines, compressors, heat exchangers, generators, vehicles, turbines, pumps, marine and aircraft engines, and so on. Although these machines are fairly durable and well-designed, shafts in operation are occasionally susceptible to significant flaws that appear without warning. When there is bearing misalignment, shaft bow, mass unbalance, or cracks, such rotor shafts are considered faulty.

Nomenclature AMB Active magnetic bearing ANN Artificial neural network BF Bayesian fusion CMS Component mode synthesis DDC Direct digital controller EL Energy location EMD Empirical mode decomposition FD Fractal dimension FE Finite element FFT Fast Fourier transform

GMA Gaussian multiscale analysis GSM Gapped smoothing method KICA Kernel independent component analysis LCF Low cycle fatigue MAL Modal analysis location MRA Multi resolution analysis ODS Operational deflection shape POM Proper orthogonal modes PSD Power spectral density RBF Radial basis function SCDS Superharmonic characteristic deflection shape SDE Stochastic differential equation SVD Singular value decomposition TOA Time of arrival

WNN Wavelet neural network WPT Wavelet packet transform WT Wavelet transform

1.1. Types of rotor defects Rotor defects due to misalignment: Here the axes are not collinear as shown in Fig. 1. It means that the shaft is not in the exact positional state as it is intended to be due to wrong fixturing, or due to inconsistency in the bearings’ dimensions or positions.