PSI - Issue 61

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Procedia Structural Integrity 61 (2024) 3–11 Structural Integrity Procedia 00 (2024) 000–000 Structural Integrity Procedia 00 (2024) 000–000

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© 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 scientific committee of IWPDF 2023 Chairman Abstract Titanium alloys, due to their advantageous properties are used to construct key components in aero-engines. However, their suscep tibility to dwell fatigue conditions has been known to lead to a severe reduction in functional life, necessitating a comprehensive understanding of the underlying micro-mechanisms. In order to examine this phenomenon, a rate dependent crystal plasticity (CP) model is coupled with a phase field fracture framework to simulate the nucleation and subsequent propagation of cracks in rep resentative volume elements made up of HCP (hexagonal-closed packed) titanium grains. The evolution of damage is studied in both static and dwell loading conditions and crack nucleation at interactions between highly misoriented grains is analyzed. The numerical framework is found capable of simulating crack initiation and intra / inter granular propagation in crystal plasticity finite element (CPFE) simulations. The model is able to capture the load shedding phenomenon at soft-hard grain interactions under cyclic loading with dwell time. The majority of the damage is observed to be taken during the dwell period rather than during loading and unloading. © 2024 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 the scientific committee of IWPDF 2023. Keywords: Crystal Plasticity; Phase Field Fracture; Dwell Fatigue 3rd International Workshop on Plasticity, Damage and Fracture of Engineering Materials (IWPDF 2023) Dwell fatigue fracture in Ti microstructures through crystal plasticity and phase field fracture frameworks Orhun Bulut a , Can Erdogan a , Tuncay Yalc¸inkaya a, ∗ a Department of Aerospace Engineering, Middle East Technical University, Ankara 06800, Tu¨rkiye Abstract Titanium alloys, due to their advantageous properties are used to construct key components in aero-engines. However, their suscep tibility to dwell fatigue conditions has been known to lead to a severe reduction in functional life, necessitating a comprehensive understanding of the underlying micro-mechanisms. In order to examine this phenomenon, a rate dependent crystal plasticity (CP) model is coupled with a phase field fracture framework to simulate the nucleation and subsequent propagation of cracks in rep resentative volume elements made up of HCP (hexagonal-closed packed) titanium grains. The evolution of damage is studied in both static and dwell loading conditions and crack nucleation at interactions between highly misoriented grains is analyzed. The numerical framework is found capable of simulating crack initiation and intra / inter granular propagation in crystal plasticity finite element (CPFE) simulations. The model is able to capture the load shedding phenomenon at soft-hard grain interactions under cyclic loading with dwell time. The majority of the damage is observed to be taken during the dwell period rather than during loading and unloading. © 2024 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 the scientific committee of IWPDF 2023. Keywords: Crystal Plasticity; Phase Field Fracture; Dwell Fatigue 3rd International Workshop on Plasticity, Damage and Fracture of Engineering Materials (IWPDF 2023) Dwell fatigue fracture in Ti microstructures through crystal plasticity and phase field fracture frameworks Orhun Bulut a , Can Erdogan a , Tuncay Yalc¸inkaya a, ∗ a Department of Aerospace Engineering, Middle East Technical University, Ankara 06800, Tu¨rkiye

1. Introduction 1. Introduction

Near α (Ti-6242) and α / β (Ti-64) titanium alloys, due to their remarkable properties of low density, high specific strength, and excellent corrosion resistance, have been commonly used to produce safety-critical parts in the cold zones of various aero-engines such as the fan and compressor sections. However, they demonstrate vulnerability to dwell loading conditions, where a material is exposed to a loading and subsequent held at that load for a period during a fatigue cycle, directly leading to a reduction of several orders in the fatigue life (see Evans and Gostelow (1979); Bache (2003)). This loss in performance is measured by the dwell debit. The critical nature of dwell fatigue was first recognized in the 1970s through the premature failure of fan blades made up of near- α IMI685 Ti alloy as discussed in Near α (Ti-6242) and α / β (Ti-64) titanium alloys, due to their remarkable properties of low density, high specific strength, and excellent corrosion resistance, have been commonly used to produce safety-critical parts in the cold zones of various aero-engines such as the fan and compressor sections. However, they demonstrate vulnerability to dwell loading conditions, where a material is exposed to a loading and subsequent held at that load for a period during a fatigue cycle, directly leading to a reduction of several orders in the fatigue life (see Evans and Gostelow (1979); Bache (2003)). This loss in performance is measured by the dwell debit. The critical nature of dwell fatigue was first recognized in the 1970s through the premature failure of fan blades made up of near- α IMI685 Ti alloy as discussed in

∗ Corresponding author. Tel.: + 90-312-210-4258 ; fax: + 90-312-210-4250. E-mail address: yalcinka@metu.edu.tr ∗ Corresponding author. Tel.: + 90-312-210-4258 ; fax: + 90-312-210-4250. E-mail address: yalcinka@metu.edu.tr

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 scientific committee of IWPDF 2023 Chairman 10.1016/j.prostr.2024.06.002 2210-7843 © 2024 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 the scientific committee of IWPDF 2023. 2210-7843 © 2024 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 the scientific committee of IWPDF 2023.