PSI - Issue 42

Diego F. Mora et al. / Procedia Structural Integrity 42 (2022) 224–235

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Diego F. Mora et. al./ Structural Integrity Procedia 00 (2019) 000 – 000

analyzed meshes present small fluctuations that indicate a rather continuous growth of the crack. Only at the end of the COD curve, clear steps can be seen. 4. Conclusions Simulation of crack propagation was carried out in a thick-walled cylinder (Falsire-Merkert) subjected to PTS loading. The implemented XFEM in ABAQUS was applied on a 3D model by assuming cyclic symmetry to reduce the computational cost, since XFEM for axisymmetric case is not available in the current implementation of ABAQUS. • In case 1, for which constant critical energy release for all temperature range was considered, initial defects propagate in the cylinder under PTS and reach the maximum extend indicating through wall cracking. This behavior is not in agreement with the experimental evidence. • For case 2, in which the critical energy release depends on the local temperature, the crack growth is not only controlled by the temperature gradient but also by the local temperature at the crack tip. In case 2, the final COD is lower than for case 1, which agrees better with the experimental results. This assumption is more realistic since in reality fracture toughness is temperature dependent. However, the comparison with the (single) experiment shows that the calculated COD is somewhat overestimated. • The criterion for crack initiation is based on the lower bound of the fracture toughness and does not consider its scatter due to e.g. the microstructure. The model is expected to give conservative predictions, i.e. overestimation of COD. Acknowledgements The authors are grateful for the financial support of PROACTIV-I (Contract No. CTR-00489) project provided by the Swiss Federal Nuclear Safety Inspectorate (ENSI). References ABAQUS. 2012. "Theory Manual and User's Manual." In.: Dassault System Simulia Corp, Providence, RI, USA. Hansbo, Anita, and Peter Hansbo. 2004. 'A finite element method for the simulation of strong and weak discontinuities in solid mechanics', Computer Methods in Applied Mechanics and Engineering , 193: 3523-40. Merkert, Gerhard. 2002. 'Anwendung und Weiterentwicklung von schädigungsmechanischen Ansätzen zur Simulation des Versagensverhaltens von Thermoschockproben', Universität Stuttgart. Meslin, E., M. Lambrecht, M. Hernández-Mayoral, F. Bergner, L. Malerba, P. Pareige, B. Radiguet, A. Barbu, D. Gómez-Briceño, A. Ulbricht, and A. Almazouzi. 2010. 'Characterization of neutron-irradiated ferritic model alloys and a RPV steel from combined APT, SANS, TEM and PAS analyses', Journal of Nuclear Materials , 406: 73-83. Moës, Nicolas, John Dolbow, and Ted Belytschko. 1999. 'A finite element method for crack growth without remeshing', International Journal for Numerical Methods in Engineering , 46: 131-50. Mora, D. F., O. Costa Garrido, R. Mukin, and M. Niffenegger. 2020. 'Fracture mechanics analyses of a reactor pressure vessel under non-uniform cooling with a combined TRACE-XFEM approach', Engineering Fracture Mechanics , 238: 107258. Sievers, J., and H. Shulz. 1994. "FALSIRE Phase I: CSNI Project For Fracture Analyses of Large-Scale International Reference Experiments (Phase I)." In, 151. Köln, Germany: GRS mbH. Sievers, J., and H. Shulz. 1996. "FALSIRE Phase II: CSNI Project for Fracture Analyses of Large-Scale International Reference Experiments (Phase II)." In, 172. Köln, Germany: GRS mbH. Soneda, Naoki. 2014. Irradiation Embrittlement of Reactor Pressure Vessels (RPVs) in Nuclear Power Plants (Woodhead Publishing). Stumpfrock, L., and Nigel Taylor. 1999. 'Structural Analysis Problem Definition Document NESC-II TG3 DOC', NESC Structural Analysis Group (TG3) , 98. Yang, Xiaoyu, Stéphane Marie, Clémentine Jacquemoud, and Philippe Bompard. 2018. 'Prediction of cleavage crack propagation path in a nuclear pressure vessel steel', Engineering Fracture Mechanics , 191: 486-503.