PSI - Issue 68

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

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 68 (2025) 446–452

European Conference on Fracture 2024 A discussion on two alternative approaches to CT coupon based K 1C determination providing results comparable with ASTM E 399 Mr. Parthasarathy Iyengar a , Mr. Jon Mardaras b , Dr. Shwe Soe c, * a Airbus UK, Metal Technology, Filton (BS34 7QQ), UK b Airbus FR, Airframe Structure, M01, 26 Chem. de l'Espeissière, 31300 Toulouse, France c University of West of England, Department of Engineering, Design and Mathematics, Bristol (BS16 1QY), UK Abstract The value of Plane Strain Fracture Toughness of a material calculated in accordance with the ASTM E 399 has been noted to be a specimen size-dependent value. The size-dependency of the same with respect to ductile materials has been an area of debate both for quality testing in production and the best applicable value for new structural design of components. While in case of production quality assessment the primary challenge is the repeatability of complying results for ductile materials, for new design – it is of a representative value for the material. Crack Mouth Opening Displacement (CMOD) and the applied load are traditionally used to calculate K 1C from CT specimen by ASTM (2023). A discussion on the comparison of two K 1C equivalents is presented here based upon observations with respect to specific Aluminium alloys and their relationship with this established material indicator is explored. Equivalents considered are K 1si and round tensile specimen inspired by Sarchamy et al (1996) and Wilson (1997). While K 1si is based upon CMOD estimation by assuming a fixed amount of crack extension of 0.5 mm irrespective of tested specimen size, round specimen may be applicable when dimensionally constrained. © 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: Round; specimen; K1c; tensile; E399; E602; ASTM; CMOD; alternative; equivalent; coupon European Conference on Fracture 2024 A discussion on two alternative approaches to CT coupon based K 1C determination providing results comparable with ASTM E 399 Mr. Parthasarathy Iyengar a , Mr. Jon Mardaras b , Dr. Shwe Soe c, * a Airbus UK, Metal Technology, Filton (BS34 7QQ), UK b Airbus FR, Airframe Structure, M01, 26 Chem. de l'Espeissière, 31300 Toulouse, France c University of West of England, Department of Engineering, Design and Mathematics, Bristol (BS16 1QY), UK Abstract The value of Plane Strain Fracture Toughness of a material calculated in accordance with the ASTM E 399 has been noted to be a specimen size-dependent value. The size-dependency of the same with respect to ductile materials has been an area of debate both for quality testing in production and the best applicable value for new structural design of components. While in case of production quality assessment the primary challenge is the repeatability of complying results for ductile materials, for new design – it is of a representative value for the material. Crack Mouth Opening Displacement (CMOD) and the applied load are traditionally used to calculate K 1C from CT specimen by ASTM (2023). A discussion on the comparison of two K 1C equivalents is presented here based upon observations with respect to specific Aluminium alloys and their relationship with this established material indicator is explored. Equivalents considered are K 1si and round tensile specimen inspired by Sarchamy et al (1996) and Wilson (1997). While K 1si is based upon CMOD estimation by assuming a fixed amount of crack extension of 0.5 mm irrespective of tested specimen size, round specimen may be applicable when dimensionally constrained. © 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: Round; specimen; K1c; tensile; E399; E602; ASTM; CMOD; alternative; equivalent; coupon © 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. Tel.: +44 7825027708; fax: N/A E-mail address: Parthasarathy.Iyengar@airbus.com * Corresponding author. Tel.: +44 7825027708; fax: N/A E-mail address: Parthasarathy.Iyengar@airbus.com

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

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.2025.06.080