PSI - Issue 68

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ScienceDirect

Procedia Structural Integrity 68 (2025) 540–546 Structural Integrity Procedia 00 (2024) 000–000 Structural Integrity Procedia 00 (2024) 000–000

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European Conference on Fracture 2024 Crashworthiness Simulations with LS-DYNA Investigating the E ff ect of Strain Rate-Dependent Material Models E. Ezgi Aytimur a a Department of Mechanical Engineering, Kocaeli University, Kocaeli 41001, Turkey Abstract This study investigates the e ff ect of using strain rate-dependent material models, specifically the Johnson-Cook, Cowper-Symonds and Elastic (non-strain rate e ff ect) models, on crashworthiness simulations involving mild steel. The research examines the deformation, stress, deceleration and recovery coe ffi cients of these models under single impact simulations conducted according to regulations of NHTSA. Ansys LS-DYNA version 13.1 was used for the simulation and material parameters were obtained from the study of Sˇkrlec and Klemenc (2016) on mild steel E185. The results show various degrees of deformation where the Johnson-Cook model exhibits the lowest total deformation due to its ability to accurately capture strain rate sensitivity. Equivalent stress values show that the Johnson-Cook model has the highest stress, followed by the Cowper-Symonds and Elastic models. Deceleration values emphasize the superior prediction accuracy of the Johnson-Cook model, while restitution coe ffi cients reveal di ff erences in energy dissipation and recovery between the models. The findings emphasize the importance of selecting appropriate material models for collision simulations based on accuracy, computational e ffi ciency and complexity tolerance. While the Johnson-Cook model o ff ers improved prediction capabilities, it may require higher computational resources compared to simpler models such as the Elastic model. In conclusion, this study contributes to the understanding of material behaviour under dynamic loading conditions and provides insights for optimizing crash simulations to improve vehicle safety and structural integrity. © 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. Keywords: Crashworthiness; LS-DYNA; Johnson-Cook; Cowper-Symonds; Strain-Rate Dependence European Conference on Fracture 2024 Crashworthiness Simulations with LS-DYNA Investigating the E ff ect of Strain Rate-Dependent Material Models E. Ezgi Aytimur a a Department of Mechanical Engineering, Kocaeli University, Kocaeli 41001, Turkey Abstract This study investigates the e ff ect of using strain rate-dependent material models, specifically the Johnson-Cook, Cowper-Symonds and Elastic (non-strain rate e ff ect) models, on crashworthiness simulations involving mild steel. The research examines the deformation, stress, deceleration and recovery coe ffi cients of these models under single impact simulations conducted according to regulations of NHTSA. Ansys LS-DYNA version 13.1 was used for the simulation and material parameters were obtained from the study of Sˇkrlec and Klemenc (2016) on mild steel E185. The results show various degrees of deformation where the Johnson-Cook model exhibits the lowest total deformation due to its ability to accurately capture strain rate sensitivity. Equivalent stress values show that the Johnson-Cook model has the highest stress, followed by the Cowper-Symonds and Elastic models. Deceleration values emphasize the superior prediction accuracy of the Johnson-Cook model, while restitution coe ffi cients reveal di ff erences in energy dissipation and recovery between the models. The findings emphasize the importance of selecting appropriate material models for collision simulations based on accuracy, computational e ffi ciency and complexity tolerance. While the Johnson-Cook model o ff ers improved prediction capabilities, it may require higher computational resources compared to simpler models such as the Elastic model. In conclusion, this study contributes to the understanding of material behaviour under dynamic loading conditions and provides insights for optimizing crash simulations to improve vehicle safety and structural integrity. © 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. Keywords: Crashworthiness; LS-DYNA; Johnson-Cook; Cowper-Symonds; Strain-Rate Dependence © 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

1. Introduction 1. Introduction

Safety is important to passengers and is the primary concern of vehicle manufacturers. So, crash tests are used to determine the safety of a vehicle. Crashworthiness term is used for the capability of vehicle structures to protect occupants when a crash happens. Crashworthiness tests are applied according to regulations that are mandatory for Safety is important to passengers and is the primary concern of vehicle manufacturers. So, crash tests are used to determine the safety of a vehicle. Crashworthiness term is used for the capability of vehicle structures to protect occupants when a crash happens. Crashworthiness tests are applied according to regulations that are mandatory for

∗ Corresponding author. Tel.: + 90-262-303-3444. E-mail address: ezgi.aytimur@kocaeli.edu.tr ∗ Corresponding author. Tel.: + 90-262-303-3444. E-mail address: ezgi.aytimur@kocaeli.edu.tr

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.2025.06.094 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.