Mechanical Properties at Low and High Strain Rates of PE 16 Alloys Irradiated to 9.2 dpa

Albertini, C.; Grande, A Del; Montagnani, M.; Pachera, Alberto

doi:10.1520/stp25648s

Cited by 3 publications

(8 citation statements)

References 9 publications

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“…8) based on the idea of Albertini [13] to induce a tensile wave by abruptly releasing the elastic mechanical energy stored inside a prestressed bar has been developed at the UniBw [15]. It is planned, to use specimens based on the RILEM pull-out test (RC6) and the RILEM beam test (RC5) [14].…”

Section: Test Configurationmentioning

confidence: 99%

Experimental investigation of bond strength under high loading rates

Michal

Keuser

Solomos

et al. 2015

EPJ Web of Conferences

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Abstract. The structural behaviour of reinforced concrete is governed significantly by the transmission of forces between steel and concrete. The bond is of special importance for the overlapping joint and anchoring of the reinforcement, where rigid bond is required. It also plays an important role in the rotational capacity of plastic hinges, where a ductile bond behaviour is preferable. Similar to the mechanical properties of concrete and steel also the characteristics of their interaction changes with the velocity of the applied loading. For smooth steel bars with its main bond mechanisms of adhesion and friction, nearly no influence of loading rate is reported in literature. In contrast, a high rate dependence can be found for the nowadays mainly used deformed bars. For mechanical interlock, where ribs of the reinforcing steel are bracing concrete material surrounding the bar, one reason can be assumed to be in direct connection with the increase of concrete compressive strength. For splitting failure of bond, characterized by the concrete tensile strength, an even higher dynamic increase is observed. For the design of Structures exposed to blast or impact loading the knowledge of a rate dependent bond stress-slip relationship is required to consider safety and economical aspects at the same time. The bond behaviour of reinforced concrete has been investigated with different experimental methods at the University of the Bundeswehr Munich (UniBw) and the Joint Research Centre (JRC) in Ispra. Both static and dynamic tests have been carried out, where innovative experimental apparatuses have been used. The bond stress-slip relationship and maximum pull-out-forces for varying diameter of the bar, concrete compressive strength and loading rates have been obtained. It is expected that these experimental results will contribute to a better understanding of the rate dependent bond behaviour and will serve for calibration of numerical models.

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Section: Test Configurationmentioning

confidence: 99%

Experimental investigation of bond strength under high loading rates

Michal

Keuser

Solomos

et al. 2015

EPJ Web of Conferences

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“…To the knowledge of the authors', the first device of this kind has been developed by Albertini [5]. Note that the ratio between the pre-stretched part and the input bar is 0.75 in this version, so as to maximize the duration time.…”

Section: Introductionmentioning

confidence: 99%

“…This ratio became more or less a standard ratio to be used with this kind of set-up. The duration times of the pre-stretched technique are commonly found to be between 2 and 4 ms [2,[5][6][7][8][9]. For instance, with a duration time of 1.2 ms, it is possible to reach a strain rate of 160/s for a total strain of 0.2.…”

Section: Introductionmentioning

confidence: 99%

“…In fact, it is due to a superposition of the elastic waves' system in the input bar. By the way, the signals can still be exploited by rebuilding the incident signal [2,[5][6][7][8][9]. The rebuilt incident pulse is considered to be valid and representative of the expected one by some authors.…”

Section: Introductionmentioning

confidence: 99%

“…To the authors' knowledge, none of the presented devices [2,[4][5][6][7][8][9] allows avoiding both the superposition of the elastic waves' system and the existence of an intrinsic tail. The aim of the article is thus to propose a prestretched bar set up for the fast dynamics loading of high ductility metals, which does not feature a superposition of the elastic waves' system.…”

Section: Introductionmentioning

confidence: 99%

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Separation of the elastic waves’ system in pre-stretched bar devices

Haugou

Leconte

Morvan

2015

EPJ Web of Conferences

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Abstract. The loading mode generated by Kolsky bars apparatus is limited due to physical reasons to a duration time of around 0.4 ms. This is not suited in the characterization of high ductility metallic alloys up to fracture at moderate strain rates, since the duration time is too short. The pre-stretched bar device is a good candidate to characterize these materials up to the moderate strain rates. Unfortunately, the elastic waves are generally not separated in time at measurements points in the input bar, and post treatment leads to assumptions. A configuration of the pre-stretching conditions that ensures no superposition of the elastic waves' system developed along the input bar is thus proposed so as to fulfill standard data analysis requirements, i.e. without any assumptions. However, a drawback of the proposed device is that one of its hydraulic devices generates a loosen tail. This statement comes from a FE numerical model of the whole set-up including the generation of the loosen tail. Finally, an analytical correction to cancel the loosen tail is proposed and validated with respect to a numerical model featuring ideal pre-loading conditions.

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Advances in the Hopkinson bar testing of irradiated/non-irradiated nuclear materials and large specimens

Albertini

Cadoni

Solomos

2014

Phil. Trans. R. Soc. A.

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A brief review of the technological advances of the Hopkinson bar technique in tension for the study of irradiated/non-irradiated nuclear materials and the development of this technology for large specimens is presented. Comparisons are made of the dynamic behaviour of non-irradiated and irradiated materials previously subjected to creep, low cycle fatigue and irradiation (2, 10 and 30 displacements per atom). In particular, complete results of the effect of irradiation on the dynamic mechanical properties of AISI304L steel, tested at 20, 400 and 550°C are presented. These high strain rate tests have been performed with a modified Hopkinson bar (MHB), installed inside a hot cell. Examples of testing large nuclear steel specimens with a very large Hopkinson bar are also shown. The results overall demonstrate the capability of the MHB to efficiently reproduce the material stress conditions in case of accidental internal and external dynamic loadings in nuclear reactors, thus contributing to the important process of their structural assessment.

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Mechanical Properties at Low and High Strain Rates of PE 16 Alloys Irradiated to 9.2 dpa

Cited by 3 publications

References 9 publications

Experimental investigation of bond strength under high loading rates

Experimental investigation of bond strength under high loading rates

Separation of the elastic waves’ system in pre-stretched bar devices

Advances in the Hopkinson bar testing of irradiated/non-irradiated nuclear materials and large specimens

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