PSI - Issue 68

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ScienceDirect

Procedia Structural Integrity 68 (2025) 1216–1222 Structural Integrity Procedia 00 (2024) 000–000 Structural Integrity Procedia 00 (2024) 000–000

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European Conference on Fracture 2024 Mixed mode fracture toughness of R260Mn rail steel using Compact Tension Shear specimens Sjoerd T. Hengeveld a,b, ∗ , Davide Leonetti a , H.H. (Bert) Snijder a , Johan Maljaars a,b a Structural Engineering and Design, Eindhoven University of Technology, De Zaale 1, Eindhoven 5612 AZ, The Netherlands b Reliable Structures, TNO, Molengraa ff singel 8, Delft 2629 JD, The Netherlands Abstract Being able to describe the fracture condition of a railway rail, after a fatigue crack has initiated, is crucial for safety assessment. Rails are loaded in mixed mode. This paper concerns an experimental investigation into the mixed-mode fracture toughness of used R260Mn rail steel. Fracture toughness experiments are carried out using compact tension shear specimens. This setup allows for testing fracture in mixed mode load condition (Mode-I and Mode-II). Results are compared in terms of maximum equivalent and maximum Mode-I fracture toughness. Contrary to the commonly adopted mixed mode failure criterion of Richard (Richard et al. (2004)) it appears that mixed mode failure is best described by the maximum Mode-I stress intensity factor component for the steel grade of study. The average fracture toughness of 51 MPa √ m is obtained, for 10 mm thick specimens. European Conference on Fracture 2024 Mixed mode fracture toughness of R260Mn rail steel using Compact Tension Shear specimens Sjoerd T. Hengeveld a,b, ∗ , Davide Leonetti a , H.H. (Bert) Snijder a , Johan Maljaars a,b a Structural Engineering and Design, Eindhoven University of Technology, De Zaale 1, Eindhoven 5612 AZ, The Netherlands b Reliable Structures, TNO, Molengraa ff singel 8, Delft 2629 JD, The Netherlands Abstract Being able to describe the fracture condition of a railway rail, after a fatigue crack has initiated, is crucial for safety assessment. Rails are loaded in mixed mode. This paper concerns an experimental investigation into the mixed-mode fracture toughness of used R260Mn rail steel. Fracture toughness experiments are carried out using compact tension shear specimens. This setup allows for testing fracture in mixed mode load condition (Mode-I and Mode-II). Results are compared in terms of maximum equivalent and maximum Mode-I fracture toughness. Contrary to the commonly adopted mixed mode failure criterion of Richard (Richard et al. (2004)) it appears that mixed mode failure is best described by the maximum Mode-I stress intensity factor component for the steel grade of study. The average fracture toughness of 51 MPa √ m is obtained, for 10 mm thick specimens. © 2025 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 / ) © 2025 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 / ) © 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

Peer-review under responsibility of ECF24 organizers. Keywords: Fracture toughness; Mixed mode fracture; rail steel Peer-review under responsibility of ECF24 organizers. Keywords: Fracture toughness; Mixed mode fracture; rail steel

1. Introduction 1. Introduction

Accurately describing the fatigue crack growth rate, the fatigue crack growth direction and failure condition are crucial for determining the residual fatigue life of steel structures in general and thus also for railway rails, Zerbst et al. (2009). Squats are complex crack networks formed due to rolling contact fatigue, originating from the head of the rail, growing downwards. They are often decisive for maintenance, Magel et al. (2016). The wheel-rail contact results in a multi-axial stress state in the vicinity of the squat. The stress intensity factor (SIF) is often considered as crack driving force for determining the failure condition. It depends on the applied load, the crack length, and the geometry. The failure condition in rail steel is often governed by cleavage (brittle) fracture. Fracture toughness is the material property used to estimate the onset of brittle fracture. This fracture toughness can be mode-dependent, Richard et al. (2004). Most studies on rail steel focus on the determination of Mode-I fracture toughness, I. Vitez (1993); Christodoulou et al. (2016); Ravaee and Hassani (2007). Mode-I fracture toughness is usually determined using standardized specimens Accurately describing the fatigue crack growth rate, the fatigue crack growth direction and failure condition are crucial for determining the residual fatigue life of steel structures in general and thus also for railway rails, Zerbst et al. (2009). Squats are complex crack networks formed due to rolling contact fatigue, originating from the head of the rail, growing downwards. They are often decisive for maintenance, Magel et al. (2016). The wheel-rail contact results in a multi-axial stress state in the vicinity of the squat. The stress intensity factor (SIF) is often considered as crack driving force for determining the failure condition. It depends on the applied load, the crack length, and the geometry. The failure condition in rail steel is often governed by cleavage (brittle) fracture. Fracture toughness is the material property used to estimate the onset of brittle fracture. This fracture toughness can be mode-dependent, Richard et al. (2004). Most studies on rail steel focus on the determination of Mode-I fracture toughness, I. Vitez (1993); Christodoulou et al. (2016); Ravaee and Hassani (2007). Mode-I fracture toughness is usually determined using standardized specimens

∗ Corresponding author E-mail address: s.t.hengeveld@tue.nl ∗ Corresponding author E-mail address: s.t.hengeveld@tue.nl

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.2025.06.190 2210-7843 © 2025 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 ECF24 organizers. 2210-7843 © 2025 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 ECF24 organizers.