Blast characterization using a ballistic pendulum with a centrally mounted Hopkinson bar

Abstract

A series of laboratory-scale blast characterization experiments are presented to show the degree to which two alternative configurations of an instrumented ballistic pendulum can provide an ideal impulsive load. Both the total impulses and blast pressure histories were captured, the latter using a centrally mounted Hopkinson bar. Repeatable and consistent total impulse values were achieved, while the Hopkinson bar technique was sufficient to capture the essential shape of the blast loads, although the fine detail of the peak pressure could not be resolved due to higher mode dispersion. A short stand-off configuration produced short duration blast loads that approached an ideal impulsive load condition with near uniform impulse distributions, although the blast pressure distributions were non-uniform. Conversely, a blast tube configuration produced blast loads with near uniform pressure and impulse distributions but did not approach an ideal impulsive load condition, that is, the pressure history must be accounted for in subsequent analytical work.

Experimental Measurement of Specific Impulse Distribution and Transient Deformation of Plates Subjected to Near-Field Explosive Blasts

“…An alternative, developed in 1914 by Bertram Hopkinson, is the apparatus now known as the Hopkinson pressure bar (HPB) [9], consisting of a length of cylindrical bar which propagates an elastic stress pulse along its axis to be recorded by sensitive equipment situated a safe distance from the loaded end. Whilst it is now more commonly used in its 'split' form for high strain-rate material testing [10], the HPB is still a valuable tool for measuring highmagnitude, short-duration loading [11][12][13][14][15][16]. HPBs are used in this study at UoS to record the spatial and temporal distribution of loading acting on a rigid target located close to an explosive.…”

A review of Pochhammer–Chree dispersion in the Hopkinson bar

“…Using one-dimensional stress wave theory, Davies was able to link the longitudinal particle velocity and radial displacement to the stress in the bar, that is the applied pressure). In more recent HPB experiments, axial and/or radial strain in the bar is most frequently measured using electrical resistance or semi-conductor strain gauges mounted on the bar perimeter, for example Puckett andPeterson (2005a, 2005b), Cloete and Nurick (2016), Rigby et al (2015Rigby et al ( , 2016, Tyas and Ozdemir (2014) and Tyas et al (2016).…”

“…Gong et al (1990), Lee and Crawford (1993), Lifshitz and Leber (1994), Zhao and Gary (1997), Marais et al (2004) and Cloete and Nurick (2016), among others, have used this method to adequately correct for dispersion effects in HPB and SHPB signals.…”

An Experimental Approach to the Measurement of Wall Pressure Generated by an Underwater Spark-Generated Bubble by a Hopkinson Bar

“…rough the strain gauges tapped on the Hopkinson pressure bar, the strain in the bar can be detected, based on which the pressure loading acting on the target plate surface can be obtained. is methodology has been used by many other researchers to detect different types of pressure loadings, such as the pressure loading of the buried explosions [25][26][27][28][29], the pressure loading of the blasts in air [30], and the pressure loading due to the high-speed sand column impact [31]. As pointed out by the current authors previously [21], some improvements should be made before this methodology can be used to detect the pressure loading due to the near-field underwater explosions consisting more than one phase pressure loadings.…”