PSI - Issue 39

Nabam Teyi et al. / Procedia Structural Integrity 39 (2022) 608–623 Author name / StructuralIntegrity Procedia 00 (2019) 000–000

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common and dangerous are transverse cracks. This is because, due to mass unbalance or deflection caused by its own weight, the shaft goes through a cycle of tension and compression on each round inducing a transverse fatigue crack. The crack opens when it is in the tensile zone and closes when it is in the compressive zone (Fig. 3.). Bansode and Billore (2021) wrote an article on critical review of recent research on experimental modal analysis for crack identification and localization in rotary machine shafts. The modal analysis technique was used to find the rotary shaft’s natural frequency in their study. To detect crack depth and location, trained ML-based ANN were also used.

b) Double cracks

c) Multiple cracks

a) Single crack

Fig. 1. Rotor with single crack, double cracks and multiple cracks.

b) Slant crack

c) Transverse cracks

a) Longitudinal crack

Fig. 2. Longitudinal crack, slant crack and transverse crack.

a)

Open crack in tensile zone

b) Closed crack in compressive zone

Fig. 3. Crack behaviour in one shaft spin.

3. Cracks in beams Beam cracks like a rotor shaft crack may be single, double or multiple (Fig. 4). Cracks in beams appear near the support, such as a column or wall, due to an increase in shear stress. These cracks are even referred to as shear cracks because they are angled 45 0 from the horizontal (Fig. 5.). These beam cracks could be avoided by adding shear reinforcements near the support where the shear stress is greatest. Beam cracks caused by insufficient concrete cover or corrosion because the bending moment is greatest at this stage, cracks form near the beam’s span’s centre at an angle of 45 0 with the horizontal. If the reinforcement provided is insufficient in relation to the load that the beam is exposed to, bending stress develops, resulting in greater deflection at the beam’s middle span. When a beam is over