PSI - Issue 47

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ScienceDirect

Procedia Structural Integrity 47 (2023) 630–635 Structural Integrity Procedia 00 (2023) 000–000 Structural Integrity Procedia 00 (2023) 000–000

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© 2023 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 IGF27 chairpersons © 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 the IGF27 chairpersons. Keywords: Tensile test, dynamic test, Split Hopkinson Tensile Bar, gauge length, B500A steel. Abstract The design of structures that can withstand dynamic loads requires a deep understanding of the dynamic behaviour of materials. Natural events (hurricanes, earthquakes, snowslides, rockfalls, floods, tsunami) or human or accidental actions (impact, blast) can trigger these types of action. The Kolsky bar (or split Hopkinson bar) is universally recognised as the most appropriate method to study materials’ behaviour in the 10 2 –10 3 1 / s strain rate range. An essential requirement that has to be met in order to ensure a uniform state of stress and strain across the specimen is dynamic equilibrium. Three round trips to a specimen are generally accepted to be the necessary amount of time to reach this state. Therefore, the shorter the sample, the earlier equilibrium will be reached. Specimen gauge length is a critical factor a ff ecting both plastic strain rate and deformation capacity. An experimental investigation of gauge length influence on high strain rate tensile test results is presented in this paper. A total of three gauge lengths of B500A reinforcing steel samples were tested (5, 10 and 15 mm). In DynaMat SUPSI Laboratory, a Split Hopkinson Tensile Bar device was used to carry out the high strain-rate tests. Two sets of experiments have been conducted: the variation of plastic strain rates has been evaluated by applying the same preloading level to the pretensioned bar over three lengths; secondly, the preload has been adjusted in order to obtain the same strain rate at all gauge lengths. Dynamic tensile tests were numerically simulated to characterise the dynamics of neck inception. Plastic distributions were calculated for each gauge length and matched experimentally measured post-mortem plastic strains. While gauge lengths strongly influence engineering stress-strain characteristics, they hardly a ff ect necking dimensions. As waves propagate through a specimen, the gauge length influences the location of the necking. © 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 the IGF27 chairpersons. Keywords: Tensile test, dynamic test, Split Hopkinson Tensile Bar, gauge length, B500A steel. 27th International Conference on Fracture and Structural Integrity (IGF27) Influence of the gauge length on dynamic direct tensile test Ezio Cadoni a, ∗ , Matteo Dotta a , Daniele Forni a , Gianmario Riganti a a University of Applied Sciences and Arts of Southern Switzerland - DynaMat SUPSI Laboratory, Mendrisio 6850, Switzerland Abstract The design of structures that can withstand dynamic loads requires a deep understanding of the dynamic behaviour of materials. Natural events (hurricanes, earthquakes, snowslides, rockfalls, floods, tsunami) or human or accidental actions (impact, blast) can trigger these types of action. The Kolsky bar (or split Hopkinson bar) is universally recognised as the most appropriate method to study materials’ behaviour in the 10 2 –10 3 1 / s strain rate range. An essential requirement that has to be met in order to ensure a uniform state of stress and strain across the specimen is dynamic equilibrium. Three round trips to a specimen are generally accepted to be the necessary amount of time to reach this state. Therefore, the shorter the sample, the earlier equilibrium will be reached. Specimen gauge length is a critical factor a ff ecting both plastic strain rate and deformation capacity. An experimental investigation of gauge length influence on high strain rate tensile test results is presented in this paper. A total of three gauge lengths of B500A reinforcing steel samples were tested (5, 10 and 15 mm). In DynaMat SUPSI Laboratory, a Split Hopkinson Tensile Bar device was used to carry out the high strain-rate tests. Two sets of experiments have been conducted: the variation of plastic strain rates has been evaluated by applying the same preloading level to the pretensioned bar over three lengths; secondly, the preload has been adjusted in order to obtain the same strain rate at all gauge lengths. Dynamic tensile tests were numerically simulated to characterise the dynamics of neck inception. Plastic distributions were calculated for each gauge length and matched experimentally measured post-mortem plastic strains. While gauge lengths strongly influence engineering stress-strain characteristics, they hardly a ff ect necking dimensions. As waves propagate through a specimen, the gauge length influences the location of the necking. 27th International Conference on Fracture and Structural Integrity (IGF27) Influence of the gauge length on dynamic direct tensile test Ezio Cadoni a, ∗ , Matteo Dotta a , Daniele Forni a , Gianmario Riganti a a University of Applied Sciences and Arts of Southern Switzerland - DynaMat SUPSI Laboratory, Mendrisio 6850, Switzerland

1. Introduction 1. Introduction

Designing safe structures that can withstand dynamic loads requires a thorough understanding of the dynamic behaviour of materials. Natural events (hurricanes, earthquakes, snowslides, rockfalls, flooding, tsunamis, etc.) as well as human or accidental actions (impact, blast, fire) can cause these loads. Due to a growing number of accidents and man-made attacks, it is necessary to deeply examine the behaviour of structures under severe dynamic loading. Thus, the dynamic behaviour of materials is one of the major issues in civil engineering today, requiring extensive research Designing safe structures that can withstand dynamic loads requires a thorough understanding of the dynamic behaviour of materials. Natural events (hurricanes, earthquakes, snowslides, rockfalls, flooding, tsunamis, etc.) as well as human or accidental actions (impact, blast, fire) can cause these loads. Due to a growing number of accidents and man-made attacks, it is necessary to deeply examine the behaviour of structures under severe dynamic loading. Thus, the dynamic behaviour of materials is one of the major issues in civil engineering today, requiring extensive research

∗ Corresponding author. Tel.: + 41-58-666-6377. E-mail address: ezio.cadoni@supsi.ch ∗ Corresponding author. Tel.: + 41-58-666-6377. E-mail address: ezio.cadoni@supsi.ch

2452-3216 © 2023 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 IGF27 chairpersons 10.1016/j.prostr.2023.07.059 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 the IGF27 chairpersons. 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 the IGF27 chairpersons.