PSI - Issue 60

ScienceDirect Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com Procedia Structural Integrity 60 (2024) 286–297 Structural Integrity Procedia 00 (2023) 000 – 000

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2452-3216 © 2024 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 the ICONS 2023 Organizers 10.1016/j.prostr.2024.05.050 2452-3216 © 2024 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 the ICONS 2023 Organizers 2452-3216 © 2024 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 the ICONS 2023 Organizers © 2024 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 the ICONS 2023 Organizers Abstract Ductile fracture in structural metals and alloys comprises of three distinct stages: namely nucleation, growth, and coalescence of voids. In this failure mode voids, either pre-existing in the material or nucleated during deformation grow until they coalesce to form a continuous fracture path. The larger voids nucleating early in the deformation history are often referred to as the primary voids whereas the smaller ones (typically around 0.1 to 0.01 times the size of the primary voids) nucleate much later and are described as the secondary voids. As the imposed deformation increases, voids grow, and the ductile crack path is influenced by the interaction and coalescence of the two-scale voids. The present work numerically models the interaction between the two populations of pre-existing voids lying ahead of the crack tip. The influence of secondary voids attributes, in particular, the shape and distribution of secondary voids on ductile crack propagation is analysed. A plane-strain modified boundary layer (MBL) model, under small-scale yielding condition, subjected to remote mode-I loading is analysed. Both primary and secondary voids lying near the crack tip are modelled explicitly. In the absence of secondary voids, as expected, the crack path is controlled by the distribution of primary voids. The presence of small secondary voids, however, influences the crack growth and, hence, the crack driving force. Various initial configurations of secondary voids are modelled and some details of crack propagation and the numerically computed driving force versus crack extension (J- Δ a) curves are presented. Keywords: Ductile fracture; Elastic-plastic solids; Finite element analysis; Small-scale yielding; two population of voids . 1. Introduction One of the important failure mechanisms in structural metals and alloys, when deformed at ambient temperature, is ductile fracture. In this failure mode voids, either pre-existing in the material or nucleated during deformation, grow until they coalesce to form a continuous fracture path (Tipper CF, 1949). Typically, void nucleation occurs first at relatively large size particles or inclusions such as MnS in 4340 high strength steel (Cox, 1974; Garrison, 1987) and intermetallic in case of aluminium alloys (Hahn, 1975). The larger Abstract Ductile fracture in structural metals and alloys comprises of three distinct stages: namely nucleation, growth, and coalescence of voids. In this failure mode voids, either pre-existing in the material or nucleated during deformation grow until they coalesce to form a continuous fracture path. The larger voids nucleating early in the deformation history are often referred to as the primary voids whereas the smaller ones (typically around 0.1 to 0.01 times the size of the primary voids) nucleate much later and are described as the secondary voids. As the imposed deformation increases, voids grow, and the ductile crack path is influenced by the interaction and coalescence of the two-scale voids. The present work numerically models the interaction between the two populations of pre-existing voids lying ahead of the crack tip. The influence of secondary voids attributes, in particular, the shape and distribution of secondary voids on ductile crack propagation is analysed. A plane-strain modified boundary layer (MBL) model, under small-scale yielding condition, subjected to remote mode-I loading is analysed. Both primary and secondary voids lying near the crack tip are modelled explicitly. In the absence of secondary voids, as expected, the crack path is controlled by the distribution of primary voids. The presence of small secondary voids, however, influences the crack growth and, hence, the crack driving force. Various initial configurations of secondary voids are modelled and some details of crack propagation and the numerically computed driving force versus crack extension (J- Δ a) curves are presented. Keywords: Ductile fracture; Elastic-plastic solids; Finite element analysis; Small-scale yielding; two population of voids . 1. Introduction One of the important failure mechanisms in structural metals and alloys, when deformed at ambient temperature, is ductile fracture. In this failure mode voids, either pre-existing in the material or nucleated during deformation, grow until they coalesce to form a continuous fracture path (Tipper CF, 1949). Typically, void nucleation occurs first at relatively large size particles or inclusions such as MnS in 4340 high strength steel (Cox, 1974; Garrison, 1987) and intermetallic in case of aluminium alloys (Hahn, 1975). The larger Third International Conference on Structural Integrity 2023 (ICONS 2023) Effect of Shape and Distribution of Secondary Voids on Ductile Crack Path A.K. Dwivedi a, * , I.A. Khan a, b , J. Chattopadhyay a, b a Homi Bhabha National Institute, Mumbai, 400094, India b Reactor Safety Division, Bhabha Atomic Research Center, Mumbai 400085, Inidia Third International Conference on Structural Integrity 2023 (ICONS 2023) Effect of Shape and Distribution of Secondary Voids on Ductile Crack Path A.K. Dwivedi a, * , I.A. Khan a, b , J. Chattopadhyay a, b a Homi Bhabha National Institute, Mumbai, 400094, India b Reactor Safety Division, Bhabha Atomic Research Center, Mumbai 400085, Inidia * A.K. Dwivedi. Tel.: +0222-5591517; fax: +0-000-000-0000 . E-mail address: akdwivedi@barc.gov.in, alok92.dwivedi@yahoo.com * A.K. Dwivedi. Tel.: +0222-5591517; fax: +0-000-000-0000 . E-mail address: akdwivedi@barc.gov.in, alok92.dwivedi@yahoo.com