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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for the features of torsional vibration as well as reasons for crack failures in a cracked rotor system. The fundamental frequency and harmonic components of the transverse cracked rotor system had larger amplitudes (particularly for the open crack), while the slant fracture had substantial later-torsional vibration (especially for the breathing crack). According to Ranjan et al. (2021), the Multiple Harmonic Influence Coefficient Method (MHICM), full-spectrum rotor responses and excitation forces are required to establish rotor fault characteristics. Without understanding the rotor system, it is feasible to predict additive fracture stiffness, residual unbalances, or internal damping. Since AMB was a part of the rotor system, it was able to commence multi-harmonic excitation. AL-Shudeifat and Alhammadi (2021) investigated negative potential energy content analysis in cracked rotors whirl response in Jeffcot/de Laval model. The numerical and experimental whirl responses of their investigation showed strong negative stiffness content throughout a wide range of rotational speeds and unbalance force vector angles. As a result, the broken rotor system exhibited large amounts of negative stiffness content, putting it at danger of premature collapse. Pertinent observations from the above mentioned literatures for the period 2019 to 2021 as pointers for probable research are presented in Table 4.

Table 4. Analysis of literatures between 2019 to 2021 for work progress Author(s), year

Scope for improvement

Xie et al., 2019

Fracture flaws can be missed because of the confusion caused by instantaneous-whirl characteristics such as misalignment, oil whirl, or rubbing. The more the diagnostic markers that can be analysed to complement one another, the better the crack diagnosis will be able to be made.

Hein and Jaanuska, 2019

A few other machine learning models may be trained for comparisons.

Shravankumar and Tiwari, 2019

The crack may be modelled using non-linear or stochastic methods, and parameter estimation can be carried