Abstract
Abstract. This article discusses the influence of the thickness of the damping rings used for interrupting a dynamic tension experiments on the results of a modified split Hopkinson tension bar (SHTB). In this paper a device enclosed in an external fixture used for interrupting a dynamic tension experiment in a SHTB is studied. The novelty of this manuscript with respect to previous studies lies in the fact that the dynamic tension experiment in a SHTB is interrupted in order to study the mechanical behavior of the material at high strain rates. The role played by such device is to interrupt the experiment at different levels of plastic deformation, particularly when the specimen is about to reach its failure strength. Finite-element (FE) simulations of high-strain-rate tension experiments are accomplished on a particle-reinforced metal matrix composite specimen (namely SiC-reinforced ZC71 magnesium alloy) when varying the thickness of the damping rings. Interrupting the test before the specimen breaks offers the possibility of being able to study in a more detailed way the deformation process of such material at high strain rates. Therefore, this work focuses on the study of the behaviour of materials undergoing high strain rates, developing a tool which allows materials to withstand different levels of strain rates in a controlled manner and providing guidance for future studies. In view of this research, it can be concluded that the thickness of the damping rings is a factor that can resolutely influence the interrupted dynamic tension experiment results avoiding the specimen's failure by optimally buffering the experiment using 0.8 mm thick lead damping rings.
Highlights
The emergence of metallic matrix composites (MMCs) has been one of the major innovations in materials during the last 30 years, since they combine an excellent mechanical behaviour with a light weight
Different authors have been testing materials at high-strain rates (Nicholas, 1981; Staab and Gilat, 1990), and experimental research of the deformation of Hopkinson bar specimens have been accomplished (Thakur et al, 1996; Verleysen and Degrieck, 2004), the novelty of this research with respect to previous studies lies in the fact that the dynamic tension experiment in a split Hopkinson tension bar (SHTB) is interrupted in order to study the mechanical behavior of the material at high strain rates
The properties to be introduced in ABAQUS were collected from the stress-strain curve obtained from other SHTB experiments accomplished on SiC-reinforced ZC71 magnesium at 600 s−1 (Essa and Pérez, 2003; Essa et al, 2003)
Summary
The emergence of metallic matrix composites (MMCs) has been one of the major innovations in materials during the last 30 years, since they combine an excellent mechanical behaviour with a light weight. In terms of the shape of the reinforcement, an initial classification for these materials can be established, i.e., fiber-reinforced MMCs (FMMCs) and particle-reinforced MMCs (PMMCs) This article shows both analytically and experimentally the use of an interruption mechanism based on the use of a damping element made of lead enclosed within an interruption fixture inside a modified split Hopkinson tension bar which can absorb the impact energy by deforming plastically. The interruption mechanism is based on the use of two damping rings working as buffers which are enclosed in an external interruption fixture They can absorb the impact energy by deforming plastically and allowing a tensile stress distribution in the specimen. The system developed in 2003 included damping rings to attenuate the effects of the compressive waves produced as a result of including the external interruption fixture In such modified SHTB apparatus, the bars were designed with a non-uniform cross section. Such increment in the cross-sectional area of the above-mentioned bar ends does not significantly interfere with the classical SHTB apparatus behaviour
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