Kolsky bar

To extend pulse calorimetry to selected mechanical properties, NIST has developed a new apparatus called the pulse-heated Kolsky bar, or split-Hopkinson pressure bar apparatus [127, 128]. The combination of the two techniques produces high-rate dynamic loading, while simultaneously pulse heating the specimen with electrical current. 

The Kolsky bar test consists of holding a small sample of the material to be tested between two long steel bars. The first bar (called the incident bar) is impacted on the end with a striker bar fired from a small airgun. This impact... 

D. Basak, H.W. Yoon, R. Rhorer and T. Bums, Microsecond Pyrometry during Rapid Resistive Heating of Samples in a Kolsky Bar Apparatus, in Temperature Its Measurement and Control in Science and Industry 7(2), (Ed. D. C. Ripple), AIP Conference Proceedings, Volume 684, Melville, 2003, 753-757. 

Chen, R., Huang, S., Xia, K., Lu, F. (2009). A modified Kolsky bar system for testing ultrasoft materials under intermediate strain rates. The Review of Scientific Instruments, 80. 

The thermodynamic properties of the gases were calculated using the method of Kolsky et al. (1957). All values given correspond to the 2010 Fundamental Craistants (Mohr et al., 2011) and to one bar standard state pressure ... 

The version of the apparatus used nowadays was introduced by Kolsky (1963), who added a second bar, from which the name Split Hopkinson Pressure Bar comes from the specimen of material to be tested is inserted between the two bars, as shown schematically in O Fig. 21.5a. The projectile, usually fired by means of a pneumatic gun, impacts the first bar (incident bar), generating the incident pulse which, at the bar/specimen interface, is partially reflected and partially propagates in the specimen. From the specimen, the pulse is transmitted to the second bar (transmitter bar). The situation is described graphically by the so-called Lagrangian diagram presented in O Fig. 21.5b. A concrete example of Split Hopkinson pressure bar is shown inO Fig. 21.6. The pulses are measured by means of strain gages placed on both incident and transmitter bar thus, their time history can be stored by means of a transient recorder, usually a digital oscilloscope or an acquisition board. From such measurements the stress (a), strain (e), and strain rate (s) in the specimen can be obtained as... 

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