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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the step despite noise in forced answers. The key takeaways of the above mentioned literatures from 2010 to 2012 as prospect for further research are presented in Table 1.

Table 1. Analysis of literatures between 2010 to 2012 for work progress Author(s), year Possibility of improvement Karthikeyan and Tiwari, 2010

End conditions (such as cantilever) and flaw models (which take defect thickness into account along with flaw depth) could be changed to test the suggested method. Smaller defects in algorithms may be developed.

Srinivas et al., 2010

May be tried on more applications and seek the success rate percentage for update of the model.

Barella et al., 2011

To be even more precise, steam turbines in use should undergo accurate non destructive testing to check for early stage fatigue cracks. The seal box has to be redesigned to prevent water from entering the shaft-flange transition zone. Non destructive inspection of the transition zone status at a periodical interval should be reformed with increased frequency. There must be a better understanding of the numerous types of faults that can exist in a motor assembly and how to distinguish between them utilising the timing system at the tip. It's important to know the differences between the characteristics of a breathing crack and an open crack on the rotor, because diagnosing a cracked rotor solely based on changes in the critical speed can lead to inaccurate results. It's possible that one can find a solution to this problem.

Momcilovic et al., 2011

Chana et al., 2011

Cheng et al., 2011

Dong and Chen, 2011

Non stationary rotating rotors may be considered for further investigation and model development.

Kulesza and Sawicki, 2012

Amplitudes of combination frequencies and induced coupled axial and torsional vibrations are very low and these may be decently elevated for further study. Results obtained by the present Floquet analysis cannot be assumed as valid for all rotating machines affected by transversal cracks. So here is the further scope for research.

Ricci and Pennacchi, 2012

Rubio and Fernández-Sáez, 2012 Singh and Tiwari, 2012

The technique may be improved to obtain better and more refined results.

More steps and cracks may be included in the model to reproduce real life cases.

3. Relevant literatures from 2013 to 2015 Guo et al. (2013) proposed an early crack detection method for Jeffcott/de Laval rotors with transverse breathing cracks. The cracked rotor's dynamic behaviour at 1/3 and 1/2 sub-critical speeds was studied using empirical EMD and WT spectra. An early detection of the breathing crack might be made by varying the average amplitudes of the 3× and 2× super-harmonic components. Liu and Jiang (2013) studied the properties of normal, transverse, and slant fractured rotors under torsional excitation. They also evaluated broken rotors with transverse and slant cracks for lateral and torsional vibrations, as well as torsional excitation. It affected 1× and coupled frequency, while the slant crack affected 2×. The crack also influenced the torsional responses. Wang et al. (2013) combined KICA with WNN to locate the source of cracks in turbine blades. On-site acoustic emission acquisition equipment was used to examine KICA input parameters. TOA, EL and MAL were evaluated. They accurately identified all crack regions, lowered data transmission and storage costs, and improved source location. With a notch, Zapico-Valle et al. (2013) applied a model-based technique for rotor fracture location and assessment. This was done while a 3-D finite element model generated data for the net. The sensitivity analysis was done for any notch size and position. For notch depths more than 20% of the rotor diameter, the model predicted position and depth, as well as rotor blind areas. Wan et al. (2014) used computer simulation to investigate the impacts of tooth crack propagation on the vibration response of a gear-rotor system with spur gears in order to determine the influence of gear crack damage on gear case vibration. Dynamic modelling helped decipher the diagnostic information in vibration signals. But the theoretical model was not the test bench. There were some discrepancies between simulation and experiment. Castejón et al.