In situ velocity and stress characterization of a projectile penetrating a sand target: Experimental measurements and continuum simulations

Borg, John P.; Morrissey, Michael; Perich, C.A.; Vogler, Tracy; Chhabildas, L.C.

doi:10.1016/j.ijimpeng.2012.07.009

Cited by 63 publications

(23 citation statements)

References 33 publications

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“…A recent promising example of in situ stress measurements during impacts on sand targets is given by Borg et al . []. However, the impact experiments in this study were conducted at very low projectile velocities in the order of 100–200 m/s.…”

Section: Introductionmentioning

confidence: 99%

In situ measurements of impact-induced pressure waves in sandstone targets

Hoerth

Schäfer

Nau

et al. 2014

J. Geophys. Res. Planets

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In the present study we introduce an innovative method for the measurement of impact-induced pressure waves within geological materials. Impact experiments on dry and water-saturated sandstone targets were conducted at a velocity of 4600 m/s using 12 mm steel projectiles to investigate amplitudes, decay behavior, and speed of the waves propagating through the target material. For this purpose a special kind of piezoresistive sensor capable of recording transient stress pulses within solid brittle materials was developed and calibrated using a Split-Hopkinson pressure bar. Experimental impact parameters (projectile size and speed) were kept constant and yielded reproducible signal curves in terms of rise time and peak amplitudes. Pressure amplitudes decreased by 3 orders of magnitude within the first 250 mm (i.e., 42 projectile radii). The attenuation for water-saturated sandstone is higher compared to dry sandstone which is attributed to dissipation effects caused by relative motion between bulk material and interstitial water. The proportion of the impact energy radiated as seismic energy (seismic efficiency) is in the order of 10 À3 . The present study shows the feasibility of real-time measurements of waves caused by hypervelocity impacts on geological materials. Experiments of this kind lead to a better understanding of the processes in the crater subsurface during a hypervelocity impact.

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Section: Introductionmentioning

confidence: 99%

In situ measurements of impact-induced pressure waves in sandstone targets

Hoerth

Schäfer

Nau

et al. 2014

J. Geophys. Res. Planets

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“…In so doing, a cross-section of the early time impact and penetration event, including the cavity formation, could be photographed in real time. A similar technique was used in the exploration of low speed impacts and impact crater formation due to small charge explosives [25,26,27]. Given the small change in impedance between the sand and the view window, as well as the small change in transmitted stress signals collected in both semi-infinite and infinite target configurations, we believe the effects of the view window to be small with regard to the transmitted stress signals, the formation of force changes and grain fracture [25].…”

Section: Methodsmentioning

confidence: 99%

“…Finally the grain catastrophically fractures and shatters into many smaller shards in 96.1 μs (not shown). For more explanation of the experimental setup and a description of this event the interested reader is directed towards two references [25,29] There are multiple bright spots that emanate from the fractured shards. Note fracture time is quite small and it has fractured near the same location from which it started.…”

Section: -4mentioning

confidence: 99%

In situ characterization of projectile penetration into sand targets

Borg¹,

Sable²,

Sandusky³

et al. 2017

AIP Conference Proceedings

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Abstract. This work presents the results from dynamic penetration experiments in which long rod projectiles were launched into Ottawa sand at velocities ranging from 90 m/s to 350 m/s. A unique aspect of these experiments was that the sand targets were visually accessible, which allowed for the penetration event recorded using high-speed digital photography. The images were processed using two different correlation methods. In addition, stress measurements of the transmitted waveforms were simultaneously collected from a piezoelectric load cell that was buried in the sand at various locations relative to the shot line. The results indicate that impact results in two waves: one similar to a detached bow shock and one near the projectile that forms force chains. Grains are damaged and broken by the force chains which allows the projectile to penetrate the target.

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“…The presence of the side wall had little effect on penetration dynamic [4]. The shot line angle of the gas gun was adjustable.…”

Section: Methodsmentioning

confidence: 99%

Experimental investigation on ballistic stability of high-speed projectile in sand

Zhang¹,

Huang²,

Qi³

et al. 2017

AIP Conference Proceedings

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Abstract. The investigation on ballistic stability of high-speed projectile in granular materials is important to study the EPW (earth-penetrating weapon). Laboratory-scaled sand entry experiments for the trajectory in the sand have been performed at a range of velocities from 30 m/s to 150 m/s. In addition, pressure sensor was embedded in the sand to record the sand stress which reflects the penetration performance of projectile during the impact. The slender projectiles were designed into flat nose shape with three kinds of L/D (length-diameter ratio) to make comparisons on the trajectory when those projectiles were launched at normal and oblique impact angles (0~25deg) along a view window. A high-speed camera beside window was employed to capture the entire process of projectiles' penetration. Basing on the comparison of different tests, theoretical analysis is carried out on the relationship between ballistic stability and associated conditions. By utilizing DIC technique, the vector field of sand velocity was acquired, and the spreading direction of the impacting energy was observed. It can be concluded that the sand stress is the function of penetrating velocity, L/D and the shot angle. It increases with the growing of penetrating velocity and L/D, decreases with the shot angle. To a certain extent, the biggest initial velocity leads to the highest stress.

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In situ velocity and stress characterization of a projectile penetrating a sand target: Experimental measurements and continuum simulations

Cited by 63 publications

References 33 publications

In situ measurements of impact-induced pressure waves in sandstone targets

In situ measurements of impact-induced pressure waves in sandstone targets

In situ characterization of projectile penetration into sand targets

Experimental investigation on ballistic stability of high-speed projectile in sand

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