The split Hopkinson bar is a well-known apparatus for performing tests at high strain-rate on engineering materials. The specimen is placed between two long bars and quickly loaded by a pressure wave, which travels at sound speed along the input bar, passes through the specimen, then is partly reflected and partly transmitted to the output bar. In the classical version, the input wave is generated by the impact of a striker bar against the input bar at a given velocity. In the direct version of the Hopkinson bar, the wave is generated by pre-loading and releasing a portion of the input bar. However, with this approach the rise time of the pressure wave is usually longer respect to the classical version. In this paper, an innovative wave generation system is presented, which exploits the abrupt shear fracture of a thin brittle disc. In this way, the rise time of the incident waves can be close to that obtained by the classical impact-based Hopkison bars (80 µs instead of 50 µs). Moreover, both tension and compression tests can be carried out with the same experimental system.

Design of an Innovative System for Wave Generation in Direct Tension–Compression Split Hopkinson Bar

Mancini E.;
2015

Abstract

The split Hopkinson bar is a well-known apparatus for performing tests at high strain-rate on engineering materials. The specimen is placed between two long bars and quickly loaded by a pressure wave, which travels at sound speed along the input bar, passes through the specimen, then is partly reflected and partly transmitted to the output bar. In the classical version, the input wave is generated by the impact of a striker bar against the input bar at a given velocity. In the direct version of the Hopkinson bar, the wave is generated by pre-loading and releasing a portion of the input bar. However, with this approach the rise time of the pressure wave is usually longer respect to the classical version. In this paper, an innovative wave generation system is presented, which exploits the abrupt shear fracture of a thin brittle disc. In this way, the rise time of the incident waves can be close to that obtained by the classical impact-based Hopkison bars (80 µs instead of 50 µs). Moreover, both tension and compression tests can be carried out with the same experimental system.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11697/150457
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