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Experimental techniques for the Hopkinson bar
AIP Conference Proceedings, 2000Several factors influence the accuracy of results when using the Split Hopkinson bar. These include longitudinal wave dispersion, and impedance mismatch of the bars with the specimens. In this paper, we discuss our approach to choosing specimen dimensions based on their impedance, thereby improving the transmitted stress signal-to-noise ratio.
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1999
Most materials show a significant change in mechanical behaviour as the rate of strain (the deformation rate) is increased1 (see High Strain Rate Effects). This is particularly evident at the high strain rates (>102 s −1) which occur under impact or explosive loading conditions.
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Most materials show a significant change in mechanical behaviour as the rate of strain (the deformation rate) is increased1 (see High Strain Rate Effects). This is particularly evident at the high strain rates (>102 s −1) which occur under impact or explosive loading conditions.
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Split Hopkinson Bar Measurements of PBXS
AIP Conference Proceedings, 2004Room temperature stress‐strain curves were measured for the polymer bonded explosive (PBX) EDC 37 at strain rates between 400 s−1 and 4000 s−1. The material was found to exhibit strong strain rate dependence in this region, the strength increasing linearly with increasing rate.
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Split Hopkinson Pressure Bar Graphical Analysis Tool
Experimental Mechanics, 2016An open-source Split Hopkinson Pressure Bar graphical data analysis tool has been developed. Written in Matlab®, the code can be freely distributed either as an executable binary or editable Matlab files. Beginning with raw voltages from two strain gages along with the incident/transmitted bars’ mechanical and geometrical properties, the user can ...
D.K. Francis +5 more
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HOPKINSON BAR STUDIES OF A PBX SIMULANT
AIP Conference Proceedings, 2008Experiments were carried out, at a strain rate of 1600 s−1, to characterise an HTPB/sugar propellant simulant within the temperature range of 50 °C to −100 °C. Optical techniques, namely high‐speed photography with digital speckle analysis for flow visualisation, and line‐laser occlusion to measure diametric expansion, were deployed.
Daniel R. Drodge +8 more
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Dynamic Fracture Toughness Test Using Hopkinson Bar
2012Various loading and measuring configurations have been developed in Hopkinson bar fracture toughness experimental techniques. It is well known that several fundamental issues, such as force equilibrium, pulse shaping, stress-wave propagation, etc., must be evaluated in order to obtain a reliable measurement.
Wei-Yang Lu, Bo Song, Kenneth Gwinn
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An innovative electromagnetic compressive split Hopkinson bar
International Journal of Mechanics and Materials in Design, 2009This paper proposes a new design for the compressive split Hopkinson bar that makes use of the intense pressure created in a transient magnetic field formed by the passage of a pulse of electric current through a series of coils. The proposed technology enables to characterize the behaviour of materials under high strain-rates with a small acceleration
C. M. A. Silva +2 more
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Discussions on Standardization of Hopkinson Bars Technique
2007It is well known that the constitutive behaviour of most materials exhibits rate sensitivity and that the rate dependent (tensile/compressive) properties of such materials should be experimentally studied. The Split Hopkinson Bar (SHB) technique has been successfully applied to investigate the visco-elastic and visco-plastic behaviour of plastics and ...
L. M. Yang, Li Song, Li-Li Wang
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Strain Measuring System for Hopkinson Pressure Bar
2007 8th International Conference on Electronic Measurement and Instruments, 2007A combination mode of host computer and slave computer is adopted by strain measuring system for Hopkinson pressure bar. The host computer is a microcomputer mode Pentium 4 which can be used in after-processing of measurement,while the 8098 single microcomputer used by the slave computer as controller, and data acquisition consists of sensors ...
Huang Wenyun, Huang Xinmiao
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The Origins of the Hopkinson Bar Technique
2018Although Bertram Hopkinson had a research interest in the dynamic strengths of materials, the bar technique he published in 1914 was developed to roughly determine the shapes of stress pulses produced by bullet impact and explosions. His pressure bar proved useful to the British explosives and armour industry during the Great War allowing them to ...
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