PSI - Issue 68

ScienceDirect Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com Procedia Structural Integrity 68 (2025) 379–385

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European Conference on Fracture 2024 Assessment of the Structural Parameters Significance Using the Experiment Design in the Production of Pressure Vessel Heads Nedeljko Vukojević a *, Zlatan Ištvanić b , Fuad Hadžikadunić a , Mustafa Hadžalić c , Amna Bajtarević-Jeleč a a University of Zenica, Faculty of Mechanical Eng., Fakultetska 1, 72000 Zenica, Bosnia and Herzegovina b Metacomm Jajce Ltd., Bage 5, 70100 Jajce, Bosnia and Herzegovina c University of Zenica, Kemal Kapetanović Institute, Travnička 7, 72000 Zenica, Bosnia and Herzegovina Abstract The production of pressure vessel heads by the incremental sheet forming (ISF) causes local deformation and surface hardening. This phenomenon, special in combination with welding and residual stresses, can cause the appearance of brittle fracture. The focus of the research is the heat-affected zone in the welded joint. Using the experiment design and plan matrix, the experimental determination of the fracture toughness, K Ic , as well as the total impact energy KV on the specimens taken from the plastically deformed vessel heads is carried out. A three-factor experiment plan is applied in two blocks, with and without post weld heat treatment (PWHT). Two output parameters, K JIC and KV, were analysed. The influence of the combination of analysed input parameters on the parameter KV exists, as indicated by the good agreement of the regression model and experimental data. At the same time, the analysis shown 'inadequate' agreement of the regression model and experimental data with the output parameter K JIC as objective function. European Conference on Fracture 2024 Assessment of the Structural Parameters Significance Using the Experiment Design in the Production of Pressure Vessel Heads Nedeljko Vukojević a *, Zlatan Ištvanić b , Fuad Hadžikadunić a , Mustafa Hadžalić c , Amna Bajtarević-Jeleč a a University of Zenica, Faculty of Mechanical Eng., Fakultetska 1, 72000 Zenica, Bosnia and Herzegovina b Metacomm Jajce Ltd., Bage 5, 70100 Jajce, Bosnia and Herzegovina c University of Zenica, Kemal Kapetanović Institute, Travnička 7, 72000 Zenica, Bosnia and Herzegovina Abstract The production of pressure vessel heads by the incremental sheet forming (ISF) causes local deformation and surface hardening. This phenomenon, special in combination with welding and residual stresses, can cause the appearance of brittle fracture. The focus of the research is the heat-affected zone in the welded joint. Using the experiment design and plan matrix, the experimental determination of the fracture toughness, K Ic , as well as the total impact energy KV on the specimens taken from the plastically deformed vessel heads is carried out. A three-factor experiment plan is applied in two blocks, with and without post weld heat treatment (PWHT). Two output parameters, K JIC and KV, were analysed. The influence of the combination of analysed input parameters on the parameter KV exists, as indicated by the good agreement of the regression model and experimental data. At the same time, the analysis shown 'inadequate' agreement of the regression model and experimental data with the output parameter K JIC as objective function. Keywords: Fracture toughness, Impact energy, Pressure vessel heads, Incremental sheet forming, Experimental design; 1. Introduction The experimental method is one of the basic scientific methods. There are four basic elements in the structure of each experiment: object, experimental methods, experimental plan and experimenter, Montgomery, D. C. (2013), Jurković, M. (1999). One of the major advantages is the possibility of determining the degree of influence (interaction) © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers Keywords: Fracture toughness, Impact energy, Pressure vessel heads, Incremental sheet forming, Experimental design; 1. Introduction The experimental method is one of the basic scientific methods. There are four basic elements in the structure of each experiment: object, experimental methods, experimental plan and experimenter, Montgomery, D. C. (2013), Jurković, M. (1999). One of the major advantages is the possibility of determining the degree of influence (interaction)

* Corresponding author - Phone: +387 61 175 998; Fax: +387 32 426 612. E-mail address: nedeljko.vukojevic@unze.ba

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers 10.1016/j.prostr.2025.06.069 2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers 2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers * Corresponding author - Phone: +387 61 175 998; Fax: +387 32 426 612. E-mail address: nedeljko.vukojevic@unze.ba