Results 191 to 200 of about 24,545 (231)

The Hopkinson Bar

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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Generalization of split Hopkinson bar technique to use viscoelastic bars

International Journal of Impact Engineering, 1994
Summary To study the high strain-rate mechanical behaviour of materials having lower wave impedance, it is suggested to generalize the split Hopkinson bar technique by using polymeric bars. The key of such a generalization lies in the method for determining the stresses and particle velocities at two interfaces of specimen from the strain pulse ...
Lili Wang, K. Labibes, Z. Azari, G. Pluvinage   +3 more
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Discussions on Standardization of Hopkinson Bars Technique

2007
It 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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The Origins of the Hopkinson Bar Technique

2018
Although 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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Dispersion Investigation in the Split Hopkinson Pressure Bar

Journal of Engineering Materials and Technology, 1990
Dispersion of an elastic wave propagating in a 76.2-mm-diameter (3 in.) Split Hopkinson Pressure Bar system was investigated with two consecutive pulses recorded in the transmitter bar. Assuming that the dispersive high frequency oscillatory components riding on the top of the main pulse originate from the first mode vibration, the dispersion was ...
J. C. Gong, L. E. Malvern, D. A. Jenkins
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Development of the polymeric split hopkinson bar technique

Journal of Applied Mechanics and Technical Physics, 2001
A compression version of the split Hopkinson bar with pressure bars and a striker, which are made of Plexiglas (a material with low density and velocity of sound) is developed. The technique is designed to determine stress—strain diagrams under high strain rates of highly deformable materials with low density and strength, such as plastics, foams, and ...
A. S. Yunoshev, V. V. Sil'vestrov
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Split Hopkinson Bar Measurements of PBXS

AIP Conference Proceedings, 2004
Room 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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An innovative electromagnetic compressive split Hopkinson bar

International Journal of Mechanics and Materials in Design, 2009
This 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, P. A. R. Rosa, P. A. F. Martins   +2 more
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Implementation of viscoelastic Hopkinson bars

2014
The properties of soft, viscoelastic materials at high strain rates are important in furthering our understanding of their role during blast or impact events. Testing these soft or low impedance materials using metallic bars in a split Hopkinson pressure bar setup, poor signal to noise ratios and impedance mismatching occur.
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Identification of Constitutive Model Parameters in Hopkinson Bar Tests

In this work, tension and compression tests have been carried out on aluminium samples at low and high strain rate, the latter performed by means of a direct tension Hopkinson bar equipment. The parameters of the Johnson-Cook constitutive model have been identified using different approaches; the first method consists in the classical Finite Element ...
Fardmoshiri M., Sasso M., Mancini E., Chiappini G., Rossi M.   +4 more
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