PSI - Issue 39

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Procedia Structural Integrity 39 (2022) 290–300

© 2021 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 CP 2021 – Guest Editors It has been confirmed in the recent studies (Kolednik et al. 2014, Tiwari et al. 2020) that the material inhomogeneity term affects the crack depending on the nature of material inhomogeneity. This effect is unknown for creep deformation and the same has been studies on idealized fracture specimen under creep deformation using configurational forces and finite element method simulating real situations of dissim lar metals us d at high temperatures in nuclear power plants and jet engines. © 2021 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) Based on the concept of configurational forces, a J -integral for elastic–plastic materials, J ep , was derived, which is able to quantify the true crack driving force in accordance with incremental theory of plasticity [4]. Hereby, the plastic strain is treated as an eigen-strain. J ep can be applied also in cases of non-proportional loading, e.g. for a growing crack (Simha et al. 2008) or for cyclic loading conditions (Ochensberger an Kolednik 2015). In this work, the concept of configurational force is applied to evaluate the crack driving force under small, medium and extensive creep conditions. Hereby, the creep strain is treated as a time dependent eigenstrain. A case study is performed where the path dependences of the elastic–plastic J -integral, J ep , and the conventional parameters C t and C* are studied for materials which undergo elastic+creep deformation, with material inhomogeneity. It has been confirmed in the recent studies (Kolednik et al. 2014, Tiwari et al. 2020) that the material inho ogeneity term affects the crack depending on the nature of material inhomogeneity. This effect is unknown for creep deformation and the same has been studies on idealized fracture specimen under creep deformation using configurational forces and finite element method simulating real situations of dissimilar metals used at high temperatures in nuclear power plants and jet engines. © 2021 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) The driving force of a crack in a non-linear elastic material is described by the conventional J -integral, J (Rice 1968). For elast ic−plastic materials, J does not describe the crack driving force. However, it describes the intensity of the crack tip field and can be, therefore, used to quantify the fracture toughness (Rice 1968). For the high-temperature behaviour of materials where creep deformation dominated, analogous parameter to J -integral were deduced, the C* -integral and a similar parameter, the C t -integral (Landes and Begley 1976). C* has been proven to have a good correlation with the creep crack growth rate for many materials, mostly under extensive creep conditions. However, it does not describe the crack driving force. Based on the concept of configurational forces, a J -integral for elastic–plastic materials, J ep , was derived, which is able to quantify the true crack driving force in accordance with incremental theory of plasticity [4]. Hereby, the plastic strain is treated as an eigen-strain. J ep can be applied also in cases of non-proportional loading, e.g. for a growing crack (Simha et al. 2008) or for cyclic loading conditions (Ochensberger and Kolednik 2015). In this work, the concept of configurational force is applied to evaluate the crack driving force under small, medium and extensive creep conditions. Hereby, the creep strain is treated as a time dependent eigenstrain. A case study is performed where the path dependences of the elastic–plastic J -integral, J ep , and the conventional parameters C t and C* are studied for materials which undergo elastic+creep deformation, with material inhomogeneity. The driving force of a crack in a non-linear elastic material is described by the conventional J -integral, J (Rice 1968). For elast ic−plastic materials, J does not describe the crack driving force. However, it describes the intensity of the crack tip field and can be, therefore, used to quantify the fracture toughness (Rice 1968). For the high-temperature behaviour of materials where creep deformation do inated, analogous parameter to J -integral were deduced, the C* -integral and a similar parameter, the C t -integral (Landes and Begley 1976). C* has been proven to have a good correlation with the creep crack growth rate for many materials, mostly under extensive creep conditions. However, it does not describe the crack driving force. 7th International Conference on Crack Paths Effect of material inhomogeneity under creep and plastic to creep transition of cracks Abhishek Tiwari a, * a Computational Fracture Mechanics Lab, Metallurgical & Materials Engineering Department, Indian Institute of Technology Ropar, Punjab, India 140001 7th International Conference on Crack Paths Effect of material inhomogeneity under creep and plastic to creep transition of cracks Abhishek Tiwari a, * a Computational Fracture Mechanics Lab, Metallurgical & Materials Engineering Department, Indian Institute of Technology Ropar, Punjab, India 140001 Abstract Abstract

* Corresponding author. Tel.: +91-1881-232410; fax: +91 - 1881 – 223395. E-mail address: abhishek.tiwari@iitrpr.ac.in * Corresponding author. Tel.: +91-1881-232410; fax: +91 - 1881 – 223395. E-mail address: abhishek.tiwari@iitrpr.ac.in

2452-3216 © 2021 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 CP 2021 – Guest Editors 10.1016/j.prostr.2022.03.099 2452-3216 © 2021 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 CP 2021 – Guest Editors 2452-3216 © 2021 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 CP 2021 – Guest Editors