PSI - Issue 80

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ScienceDirect

Procedia Structural Integrity 80 (2026) 368–377 Structural Integrity Procedia 00 (2023) 000–000 Structural Integrity Procedia 00 (2023) 000–000

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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 Ferri Aliabadi 10.1016/j.prostr.2026.02.035 ∗ Corresponding author. Tel.: +81-95-819-2492 ; fax: +81-95-819-2534. E-mail address: s-aki@nagasaki-u.ac.jp 2210-7843 © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of Professor Ferri Aliabadi. 1. Introduction In linear elastic fracture mechanics (LEFM), the stress intensity factor (SIF) is a critical parameter for evaluating structural integrity and predicting the service life of components (Irwin, 1957; Tada et al., 2000; Murakami, 2001). Compared to two-dimensional (2D) cases, the SIF for three-dimensional (3D) cracks is not a single value but exhibits a complex distribution along the crack front. This complexity stems from the combined influence of the free surface, crack geometry, loading conditions, and Poisson’s ratio ν . Therefore, a precise analysis of the SIFs for 3D cracks remains a significant challenge in LEFM. ∗ Corresponding author. Tel.: +81-95-819-2492 ; fax: +81-95-819-2534. E-mail address: s-aki@nagasaki-u.ac.jp 2210-7843 © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of Professor Ferri Aliabadi. © 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 Ferri Aliabadi Abstract This study proposes a novel numerical method based on the body force method to calculate the mode I stress intensity factor (SIF) for a deep surface crack perpendicular to a free surface. The crack is subjected to an internal pressure that is uniform in its depth direction and varies across its width direction according to a power-law distribu tion of coordinate variable. A key feature of this method is the introduction of a new fundamental density function based on the corresponding COD of a two-dimensional crack under plane strain conditions and subjected to the same internal power-law pressure distribution. This approach ensures a stable and highly accurate analysis, even for high-order internal-pressure distributions, by incorporating an analytical solution into the numerical scheme. After validating the strategy, a parametric study was performed. The influences of the Poisson’s ratio and the pressure power-law exponent on the mode I SIF distribution along the crack front, including its maximum values and their depths, were systematically computed, and the results were shown graphically. © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of Professor Ferri Aliabadi. Keywords: Surface crack; Body force method; Stress intensity factor; Vertex singularity 1. Introduction In linear elastic fracture mechanics (LEFM), the stress intensity factor (SIF) is a critical parameter for evaluating structural integrity and predicting the service life of components (Irwin, 1957; Tada et al., 2000; Murakami, 2001). Compared to two-dimensional (2D) cases, the SIF for three-dimensional (3D) cracks is not a single value but exhibits a complex distribution along the crack front. This complexity stems from the combined influence of the free surface, crack geometry, loading conditions, and Poisson’s ratio ν . Therefore, a precise analysis of the SIFs for 3D cracks remains a significant challenge in LEFM. Fracture, Damage and Structural Health Monitoring A mode-I SIF for a deep surface crack subjected to internal pressure varying with power of the coordinate variable Yohei Sonobe a , Sei Hisatsune a , Takuichiro Ino b , Atsuhiro Koyama a , Akihide Saimoto a, ∗ a Graduate School of Integrated Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 8528521, Japan b Creative Engineering Department, National Institute of Technology, Ariake College, 150 Omuta 8368585, Japan Abstract This study proposes a novel numerical method based on the body force method to calculate the mode I stress intensity factor (SIF) for a deep surface crack perpendicular to a free surface. The crack is subjected to an internal pressure that is uniform in its depth direction and varies across its width direction according to a power-law distribu tion of coordinate variable. A key feature of this method is the introduction of a new fundamental density function based on the corresponding COD of a two-dimensional crack under plane strain conditions and subjected to the same internal power-law pressure distribution. This approach ensures a stable and highly accurate analysis, even for high-order internal-pressure distributions, by incorporating an analytical solution into the numerical scheme. After validating the strategy, a parametric study was performed. The influences of the Poisson’s ratio and the pressure power-law exponent on the mode I SIF distribution along the crack front, including its maximum values and their depths, were systematically computed, and the results were shown graphically. © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of Professor Ferri Aliabadi. Keywords: Surface crack; Body force method; Stress intensity factor; Vertex singularity Fracture, Damage and Structural Health Monitoring A mode-I SIF for a deep surface crack subjected to internal pressure varying with power of the coordinate variable Yohei Sonobe a , Sei Hisatsune a , Takuichiro Ino b , Atsuhiro Koyama a , Akihide Saimoto a, ∗ a Graduate School of Integrated Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 8528521, Japan b Creative Engineering Department, National Institute of Technology, Ariake College, 150 Omuta 8368585, Japan