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

2015

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Abstract. It is unquestionable the fact that a structural system should be able to fulfil the function for which it was created, without being damaged to an extent disproportionate to the cause of damage. In addition, it is an undeniable fact that in reinforced concrete structures under severe dynamic loadings, both concrete and reinforcing bars are subjected to high strain-rates. Although the behavior of the reinforcing steel under high strain rates is of capital importance in the structural assessment under the abovementioned conditions, only the behaviour of concrete has been widely studied. Due to this lack of data on the reinforcing steel under high strain rates, an experimental program on rebar reinforcing steels under high strain rates in tension is running at the DynaMat Laboratory. In this paper a comparison of the behaviour in a wide range of strain-rates of several types of reinforcing steel in tension is presented. Three reinforcing steels, commonly proposed by the European Standards, are compared: B500A, B500B and B500C. Lastly, an evaluation of the most common constitutive laws is performed.

“…For this reason a special attention should be attended in order to simulate the structural performance of a real rebar subjected to high strain rates [16].…”

Section: Discussionmentioning

confidence: 99%

“…In case of high dynamic loadings, high strain rates in the range of 10 1 to 10 3 s −1 are generated [12][13][14][15][16]. For this reason, new information on the high strain rate behavior of modern rebars is extremely necessary [13,14].…”

Section: Introductionmentioning

confidence: 99%

Strain rate effects on reinforcing steels in tension

2015

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“…As pre-tensioned bar is used part of the input bar. On the basis of the incident (ε I ), reflected (ε R ) and transmitted (ε T ) records, of the consideration of the basic constitutive equation of the input and output elastic bar material, of the one-dimensional wave propagation theory it is possible to calculate the stress, strain and strain-rate curves by the following equations [4][5][6][7][8]:…”

Section: Experimental Set-upmentioning

confidence: 99%

“…1. It consists of two cylindrical high strength steel bars, having a diameter of 10 mm, with a length of 9 and 6 m for input and output bar, respectively and the thin sheet steel specimen is screwed to the two bars [4][5][6][7][8].…”

Section: Experimental Set-upmentioning

confidence: 99%

Influence of the temperature on the tension behaviour of EUROFER97 alloy at high strain rate

Dotta

et al. 2015

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Abstract. This paper presents an experimental investigation on the influence of the temperature on the reduced activation steel Eurofer97 under uniaxial tensile loads at high strain rate. Round undamaged specimens of this material having gauge length 5 mm, diameter 3 mm, were tested in universal machine to obtain its stress-strain relation under quasi-static condition (0.001s −1 ), and in modified Hopkinson bar to study its mechanical behaviour at high strain rates (300 s −1 , 1000 s −1 ) respectively. The tests at high strain rate were carried out at 450 • C and at nitrogen temperature. Finally, the parameters of the Zerilli-Armstrong constitutive material relationship were obtained.

“…Having fulfilled the conditions i) and ii) and being the two bars elastically loaded the one-dimensional elastic plane stress wave propagation theory can be applied to the input bar-specimen-output bar system as it is extensively shown in [4][5][6][7][8], where the three relationships are proofed which allow to calculate the stress, the strain and the strain rate in the specimen material versus time from the records of the incident (ε I ), reflected (ε R ) and transmitted (ε T ) pulses.…”

Section: High Strain Ratementioning

confidence: 99%

Experimental and numerical analysis of the dynamic behaviour in tension of an armour steel for applications in defence industry

Dotta

et al. 2015

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Abstract. The dynamic behaviour of armour steel in tension was investigated over a wide range of strain-rates on round specimens. The experiments were carried out by means of a Split Hopkinson Tensile Bar device and by a Hydro Pneumatic Machine. The target strain rate were set at the following six levels: 10 −3 , 5, 25, 100, 500 and 1000 s −1 . Two material models were calibrated and used to replicate the experiments and to simulate blasting event on steel plate. Finally, the two responses are compared.