PSI - Issue 36

Ivan Pidgurskyi et al. / Procedia Structural Integrity 36 (2022) 190–196

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Ivan Pidgurskyi, Mykola Stashkiv, Mykola Pidgurskyi et al. / Structural Integrity Procedia 00 (2021) 000 – 000

a

b Fig. 4. Dependence of on the shape parameter a/ 4c: a – position 1,2,3; b – position 4, 5, 6 in Table 1.

5. Conclusions With the increase of the crack shape parameters a/c (at the same crack size on the surface), the durability of the coalescence stage N coal decreases despite the increase of the size a coal in this zone. It was found that for small cracks (up to 40% of the thickness of the element), the duration of the coalescence stage (<8%) does not have significant effect on the residual durability of the structural element (at the studied thicknesses t = 20… 25 mm). For large major cracks, the length of which is proportio nal to the thickness of the element, the effect of the coalescence period increases to 18 - 25%, which significantly clarifies the calculation of the residual durability of the structural element. The influence of the shape factors of identical surface cracks during their coalescence on the fatigue crack growth life is indeterminate. The ratio is the largest for small cracks at a /4 c = 0.39, while for larger cracks at a /4 c = 0.10. The smallest values of for cracks of different sizes were obtained at a /4 c = 0.25. References ASME Boiler and Pressure Vessel Code Section XI: Rules for Inservice Inspection of Nuclear Power Plant Components (2005). New York, USA: American Society of Mechanical Engineering. Bayley, C.J., Bell R., 1999. Parametric investigation into the coalescence of coplanar fatigue cracks. Int. J. of Fat. 21(4), 355-360. Bezensek, B., Hancock, J.W., 2004. The re-characterisation of complex defects: Part I: Fatigue and ductile tearing, Eng. Fract. Mech 71(7 – 8), 981-1000. Bezensek, B., Sharples, J., Hadley, I., Pisarski, H., 2011. The History of BS 7910 Flaw Interaction Criteria. Proceedings of the ASME 2011 Pressure Vessels and Piping Conference . Volume 1: Codes and Standards. Baltimore, Maryland, USA., 837-843. ASME. BS7910: Guidance to Methods for Assessing the Acceptability of Flaws in Metallic Structures (2013). London: British Standards Institution. Harter, James A., 2020. AFGROW.net. Users guide and technical manual, Version 5.3.5.24 For Windows 10/8/7 LexTech, Inc., 356. Kishimoto, K., Soboyejo, W.O., Knott, J.F., Smith R.A., 1989. A numerical investigation of the interaction and coalescence of twin coplanar semi-elliptical fatigue cracks, Int. J. of Fat. 11(2), 91-96. Lin, X.B., Smith, R.A., 1999. Finite element modelling of fatigue crack growth of surface cracked plates: Part I: The numerical technique. Engineering Fracture Mechanics 63(5), 503-522. Lin, X.B., Smith, R.A., 1999. Finite element modelling of fatigue crack growth of surface cracked plates: Part II: Crack shape change. Engineering Fracture Mechanics 63(5), 523-540. Lin, X.B., Smith, R.A., 1999. Finite element modelling of fatigue crack growth of surface cracked plates: Part III: Stress intensity factor and fatigue crack growth life. Engineering Fracture Mechanics 63(5), 541-556. Lu, Kai, Li, Yinsheng, 2017. Fatigue crack growth calculations for two adjacent surface cracks using combination rules in fitness-for-service codes. AIMS Materials Science 4(2), 439-451. Pang, John H.L., Hoh, Hsin Jen, Tsang, Kin Shun, Low, Jason, Kong, Shawn Caleb, Yuan, Wen Guo, 2017. Fatigue crack propagation analysis for multiple weld toe cracks in cut-out fatigue test specimens from a girth welded pipe. International Journal of Fatigue 94(1), 158-165. Patel, S. K., Dattaguru, B., Ramachandra, K., 2010. Multiple Interacting and Coalescing Semi-Elliptical Surface Cracks in Fatigue: Part 1: FEA, SL 3(1), 37-57. Pidgurskyi, I., Stashkiv, M., Pidgurskyi, M., 2021. Investigation of the coalescence of twin coplanar semi-elliptical fatigue cracks in structural