Issue 49

R. Suresh Kumar et alii, Frattura ed Integrità Strutturale, 49 (2019) 526-535; DOI: 10.3221/IGF-ESIS.49.49 534  The numerical crack growth estimates at both specimen level as well as the component level, have been validated with better engineering accuracy with the available experimental data.  The SIF is seen to exhibit a non-monotonic variation to the crack depth ratio, attaining a peak value at a critical ‘a/t’ ratio. The estimated results show that the variation of K I for the pipe geometry decreases earlier than that of the plate geometry. This early reduction is due to the influence of the global compressive stress present at the leading edge of the crack propagation.  Fatigue crack growth rate is found to be lower for the pipe geometry than that of the plate geometry under cyclic bending condition. This is due to the presence of the higher amount of asymmetric bending stress variation in the case of the pipe bend geometry than that of the plate geometry under the application of bending moment.  The difference in material property may also influence the FCG behaviour. This can be confirmed by simulating FCG for both the plate and pipe bend geometries with identical material properties, load ratio and cyclic stress variation. In the case of the SFR piping system, the leading cause of fatigue load for crack propagation is the cyclic bending stress. The above results indicate that a prototype level simulation is essential for an accurate estimation of parameters used in the LBB demonstration. A CKNOWLEDGEMENTS uthors acknowledge the support rendered by Shri. Santhosh N L & Shri. Kaushik, DHIO Research and Engineering, Bangalore for their service related to FRANC3D software. R EFERENCES [1] Suresh Kumar, R., Jalaldeen, S., Selvaraj, P., Chellapandi, P.(2011). High Temperature Design of Class-1 Piping Systems in Sodium Cooled Fast Breeder Reactor. Transactions, SMiRT 21, 6-11 November, 2011, New Delhi, India, p. Div-VI: Paper ID# 792. [2] Afcen. (2012). Section III – Tome 1 – Subsection Z - Appendix A16 : Guide for prevention of fast fracture , Leak Before Break analysis and defect assessment, RCC MRx. [3] Chellapandi, P., Srinivasan, R., Biswas, A., Chetal, S.C., Bhoje, S.B. (2003).Leak Before Break Investigation on Sodium Piping for Prototype Fast Breeder Reactor. Transactions of the 17th International Conference on Structural Mechanics in Reactor Technology (SMiRT 17) Prague, Czech Republic, p. 3216. [4] Chapuliot, S., Chaudat, T., Mineau, V., Moulin, D. (1996). Fatigue growth of semi-elliptical cracks in plates subjected to bending, ASME PVP, Fatigue & Fracture, 323, pp 291-298. [5] Arora, P., Singh, P.K., Bhasin, V., Vaze, K.K., Pukazhendhi, D.M., Gandhi, P., Raghava, G. (2013). Fatigue crack growth behavior in pipes and elbows of carbon steel and stainless steel materials, Procedia Eng., 55, pp. 703–709. DOI: 10.1016/j.proeng.2013.03.318. [6] Singh, P.K., Bhasin, V., Vaze, K.K., Ghosh, A.K., Kushwaha, H.S., Murthy, D.S.R., Gandhi, P., Sivaprasad, S. (2008). Fatigue studies on carbon steel piping materials and components: Indian PHWRs, Nucl. Eng. Des., 238(4), pp. 801– 813, DOI: 10.1016/j.nucengdes.2007.09.002. [7] Chattopadhyay J., B. Dutta, and H.Kushwaha. (1999). Leak-before-break qualification of primary heat transport piping of 500 MWe Tarapur Atomic Power Plant, Int. J. Press. Vessel. Pip., 76(4), pp. 221–243, DOI: 10.1016/j.nucengdes.2016.02.013. [8] Sethuraman, R., C. L. Rao, and P.Kameswara R. (1999). Fatigue crack growth of semielliptical surface cracks in curved geometries, J. Structuctral Eng., 26(1), pp. 81–86, DOI: 10.1177 /0021998305055549. [9] Riddell, W.T., Ingraffea, A.R., Wawrzynek, P.A. (1997). Experimental observations and numerical predictions of three- dimensional fatigue crack propagation, Eng. Fract. Mech., 58(4), pp. 293–310, DOI: 10.1016/S0013-7944(97)00122-7. [10] Rao, C.L., Sethuraman, R., Bhoje, V., Chellapandi, P. (2000). Fatigue Crack Propagation Studies on a Semi-Elliptical Surface Crack in a Plate Subjected to Bending Loads, ASMEPVP, 404, pp. 37–44. [11] Nagapadmaja, P., Kalyanaraman, V., Kumar, S.R.S., Chellapandi, P. (2008). Experimental study on LBB behaviour of A