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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and 1/2 subcritical zones were found to be a stable feature for crack detection. For a rotor ball bearing system with a transverse crack on the rotor, Upadhyay et al. (2017) employed contact deformation theory. Bifurcation diagrams explored the effect of crack depth and size on rotor ball-bearing system dynamics. The system grew increasingly unstable as the fracture depth increased, yet as the response amplitude increased, the critical rotating speed reduced. S. Singh and Tiwari (2018) investigated AMB-supported flexible rotor systems. The identification techniques were developed using mathematical modelling of the rotor system. The algorithm was tested for robustness in a basic rotor system for measurement noise and bias errors in system parameters. A new method for simulating cracked rotor vibration was described by Spagnol et al. (2018) without assuming weight dominance. a chordal picture of decay was drawn by them. The area moment of inertia and stiffness matrix of the imbalanced broken rotor were studied. The critical speed and peak amplitude of the weight-dominant model moved virtually sinusoidally from 0° to 180°, but the proposed model's critical speed and peak amplitude gradually plateaued when the eccentric mass was placed at angles larger than 90°. The impacts of unbalance on the nonlinear dynamics of the cracked rotor were studied by Wang et al. (2018) using 3D finite element models of the shaft and the breathing crack. The CMS approach was used to minimise model order and boost computing performance. This study examined the effects of distributed unbalance on the crack breathing behaviour and the rotor's dynamic response. Based on bending theory, Xie et al. (2018) suggested an approach for computing the stiffness breathing functions of fractured Jeffcott/de Laval rotors. Time-domain waveforms, phase waterfall graphs, and time–frequency amplitude spectrums were used. The phase waterfall diagram detected high-order frequency components of broken rotors. The radial pattern in phase waterfall plots indicated fractured rotors and may be used for crack monitoring. Salient notes from the above mentioned literatures for the period 2016 to 2018 as option for potential research are presented in Table 3.

Table 3. Analysis of literatures between 2016 to 2018 for work progress. Author(s), year Scope for improvement Ferjaoui et al., 2016

The proposed method could be tried to understand the effect of a slant crack as well.

Gómez et al, 2016

The methodology proposed may be integrated in industrial equipment to study condition monitoring.