PSI - Issue 47

Zoltán Bézi et al. / Procedia Structural Integrity 47 (2023) 646–653 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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As can be seen from the table, the VCCT model works very well for the determination of fracture toughness and has many advantages over traditional testing and standard evaluation. The VCCT model also allows the evaluation of cases not covered by the standard and is a more time-efficient simulation tool due to the 2D method. 5. Conclusions and summary In the first part of the paper, the determination of the GTN parameters by the ANN method was presented using flat small specimens as opposed to the commonly used cylindrical specimens. As shown in the paper, an ideal set of parameters can be determined with this specimen, which was verified by different side notched specimens and worked well with standard CT specimens as well. In the following, a method was developed to calculate the value of the integral J continuously during the simulation. The known VCCT technique has been combined with the GTN damage model to exploit the advantages of both methods, thus the developed modelling technique allows to simulate even ductile crack propagation and even the ductile-brittle transition can be handled with this model. The great advantage of the VCCT model is that it does not propagate the crack as the elements are removed from the simulation but opens the mesh when the set critical damage value is reached, which allows continuous evaluation of the J-integral by continuously changing the crack tip. As the summary table 2 confirms, this method is capable of computing the integral J with very good accuracy, which is well applicable to non-standard cases for example transfer of material properties from small scale to large scale components. In the later work it is also planned to use this method to simulate the brittle-ductile transition zone. Acknowledgements This project has received funding from the Euratom research and training programme 2020-2024 under grant agreement No 900014 (H2020 FRACTESUS). The views and opinions expressed herein do not necessarily reflect those of the European Commission. References Aguir, H., Marouani., H., 2010. Gurson-Tvergaard-Needleman parameters identification using artificial neural networks in sheet metal blanking, Int J Mater Form 3, 113-116 ASTM E1820-20: Standard Test Method for Measurement of Fracture Toughness Butta, R., Kamaraju, M., Sumalatha, V., 2021. 4 - Heuristic methods for data clustering, In: Binu, D., Rajakumar, B.R., (Eds.) Artificial Intelligence in Data Mining, Academic Press, 65-86, Caudill, M., C. Butler, 1992. Understanding Neural Networks: Computer Explorations, Vols. 1 and 2, Cambridge, MA: The MIT Press Gurson, A., 1977. Continuum theory of ductile rupture by void nucleation and growth: part 1. Yield criteria and flow rules for porous ductile media, Journal of Engineering Materials and Technology, 99, 2 – 15. Li, J., Cheng, Jh., Shi, Jy., Huang, F., 2012. Brief Introduction of Back Propagation (BP) Neural Network Algorithm and Its Improvement. In: Jin, D., Lin, S. (Eds) Advances in Computer Science and Information Engineering. Advances in Intelligent and Soft Computing, 169. Springer, Berlin, Heidelberg. Lucon, E., 2022. Spreadsheet-Based Software for the Analysis of Unloading Compliance Fracture Toughness Tests in Accordance with ASTM E1820, NISTIR 8421 MacKay, D.J.C., 1992. Bayesian interpolation, Neural Computation, 4 (3), 415 – 447. Nielsen, R.H., 1992. III.3 - Theory of the Backpropagation Neural Network, In: Wechsler, H., (Ed) Neural Networks for Perception, Academic Press, 65-93, Rybicki, E. F., Kanninen, M. F., 1977. A finite element calculation of stress intensity factors by a modified crack closure integral, Eng. Fract. Mech. 9 (4), 931 – 938. Sarkar, T., Phyton programme source: https://github.com/tirthajyoti/doepy (Accessed 19 May 2022) Shikalgar, T.D., Dutta, B.K., Chattopadhyay, J., 2020. Analysis of p-SPT specimens using Gurson parameters ascertained by Artificial Neural Network, Engineering Fracture Mechanics 240, Tvergaard, V., Needleman, A., 1984.Analysis of the cup-cone fracture in a round tensile bar, Acta Metallurgica, 32 (1), 157-169,