A New Apparatus for Large Scale Dynamic Tests on Materials

Peroni, Marco; Caverzan, Alessio; Solomos, George

doi:10.1007/s11340-015-0123-0

Cited by 5 publications

(5 citation statements)

References 20 publications

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“…By modifying the central part of the equipment it is possible to exploit the tensile wave generated in order to perform different types of tests, as for example compression. Of course, different aspects and parts of the equipment have to be re-designed, improved and checked, as reported in [23,24]. Without entering into details, a brief description of the modified facility is illustrated here.…”

Section: Methodsmentioning

confidence: 99%

Compressive behaviour of dam concrete at higher strain rates

Caverzan

Peroni

Solomos

2016

Eur. Phys. J. Spec. Top.

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Abstract. The mechanical behaviour of concrete when subjected to impact or blast has still many aspects requiring further study. Dam concrete is characterized by large coarse aggregates, hence large specimen sizes are needed in order to study a representative volume of the material. Exploiting an innovative equipment, based on Hopkinson bar techniques, the dynamic behaviour of concrete of 64 mm maximum aggregate size has been investigated. Direct dynamic compression tests have been performed on medium and large size cylindrical samples. Full stress-strain curves have been obtained, which have allowed the estimation of fracturing energies and of the relevant dynamic increase factor. The experimental campaign has also included a reference standard concrete in order to highlight the peculiarity of the dam concrete at high strain rates and to validate the transition of this type of testing to very large specimens.

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Section: Methodsmentioning

confidence: 99%

Compressive behaviour of dam concrete at higher strain rates

Caverzan

Peroni

Solomos

2016

Eur. Phys. J. Spec. Top.

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“…Table 1 summarizes the experimental plan and the number of test replicates carried out at the Joint Research Centre (JRC). Testing for the range of strain-rates investigated and the different specimen geometries has been performed by means of three different apparatuses: a screw tensometer for the static tests and two modified Hopkinson bars for the dynamic ones [22,23]. Since tensometers and conventional Hopkinson bars are regularly used in the material characterization, only a brief description is provided below for the Hopkinson bar used for the large size specimens (geometry G3).…”

Section: Specimens and Experimental Apparatusesmentioning

confidence: 99%

Advanced Experimental Data Processing for the Identification of Thermal and Strain-Rate Sensitivity of a Nuclear Steel

Peroni

Solomos

2019

J. dynamic behavior mater.

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The knowledge of material mechanical behaviour in different physical conditions is necessary to accurately simulate structural response using finite element methods, especially when complex physical processes, such as strain-hardening, large strains etc., are involved. In this context, the material characterization at different temperatures and strain-rates is indispensable, but it is equally essential to properly transform the test data into efficient constitutive equations capable to accurately reproduce the material response. As an alternative to the conventional analytical approach of the stress-strain curve fitting, this investigation examines the adoption of an inverse method that exploits a FEM model to accurately keep account of the specimen stress, strain, and temperature fields. The material parameters of the selected constitutive model are then obtained by using an optimization algorithm that iteratively changes the parameter values to minimize a target function. The algorithm has been implemented in MATLAB using the LS-DYNA FEM solver. In the paper, this method has been applied to the experimental data produced in a test campaign (EU project LISSAC) for a ferritic steel normally employed in nuclear pressure vessels. These data refer to tensile testing under several strain-rate and temperature conditions and include both smooth and notched cylindrical specimens. The constitutive models of Johnson-Cook and Zerilli-Armstrong have been considered for the demonstration of the methodology. The efficiency of the approach in determining the model parameters is critically assessed.

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“…The split Hopkinson pressure bar (SHPB) apparatus is commonly used for this purpose. Such testing facilities have been widely used for dynamic compression, shear, torsion or tensile tests [25][26][27][28]. Incident, reflected and transmitted pulses recorded on input and output using SHPB methods allow the determination of the stress and strain state in the material sample being tested based on the data processing proposed by Kolsky [29].…”

Section: Experimental Techniques Devoted To Brittle Materialsmentioning

confidence: 99%

Brittle materials at high-loading rates: an open area of research

Forquin¹

2017

Phil. Trans. R. Soc. A.

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Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

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A New Apparatus for Large Scale Dynamic Tests on Materials

Cited by 5 publications

References 20 publications

Compressive behaviour of dam concrete at higher strain rates

Compressive behaviour of dam concrete at higher strain rates

Advanced Experimental Data Processing for the Identification of Thermal and Strain-Rate Sensitivity of a Nuclear Steel

Brittle materials at high-loading rates: an open area of research

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