A Comparison of Half and Quarter Space Penetration into Granular Media

Mechanics Research Communications, 2015

In this study, a transparent sand surrogate was employed along with high-speed imagery to un-intrusively visualize the penetration of a spherical projectile into the center of a saturated granular target, representing angular sand, at speeds ranging between 60 and 150 m/sec. The transparent sand was made by saturating an angular granular fused quartz waste product with a matched refractive index pore fluid made of sucrose. A distinct zone of opacity was observed travelling ahead of the projectile. The opacity zone appears circular during initial penetration and transitions into the shape of an elongated cone in shots with higher initial velocities. Some healing was also observed with time and some increase in transparency was observed. Some of the opacity is attributed to dilatancy of the granular fused quartz during penetration, and healing is attributed to flow of pore fluid into the dilated zone.

SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter, 2020

Penetration depth is the most important parameter in terminal ballistics. Here only the case of projectiles penetrating granular medium is considered. Laboratory and field tests have shown that projectile characteristics such as mass, size, and nose shape, and target characteristics such as strength and density determine the depth of penetration. Analyses of full flight data recorded by onboard data acquisition system (G-Rec) are presented. These tests have revealed very high decelerations at impact with extensive particle fracture along the path of the projectile. Particle size distribution analysis of the sample collected from the projectile tip shows two to three orders of magnitude reduction in size. For similar impact velocities and target densities, Poncelet's coefficient does not vary with tip shape.

Applied Sciences

The penetration to geological shield occurs in many situations at various velocities and scales, for example, meteor-cratering, pile driving, falling of objects from high-rise building construction, and debris/fragments from failed components. The soil media is an efficient energy dissipation system and effective shock protection shield. Impact circumstances are currently getting widespread attention. A lot of research has been done on soil media for impact and penetration. The phenomenon of dynamic penetration in heterogeneous particulate soil medium is very complex and the target soil media under dynamic impact especially under high speed and deep penetration neither behave completely as solid nor as liquid. The topics of recent research interest in the field of penetration to soil media and their significant findings are critically reviewed in the present study. The dedicated review of analytical, empirical, experimental, and computational methods to predict the response of soils...

Nucleation and Atmospheric Aerosols, 2020

Experiments were designed to study the terminal phase of penetration in a synthetic soft clay. Rod-cone projectiles were launched at speeds of approximately 5 m/s into a saturated soft transparent surrogate for saturated marine clay. Quasi-static tests were also performed into the same material. The average penetration resistance was 22 kPa. It was found that rate effects and shaft resistance were relatively small. A practical result is that resistance to dynamic penetration in this material can be estimated from quasi-static cone penetration tests. The stress (load/area) required to extract penetrators was very similar to the penetration resistance.

1981

A parameter analysis is performed on an analytical penetration model which has been recently developed. Figures are plotted to show how the disturbed zone size, parameters of displacement and stress fields and dynamic section pressure are dependent on soil compressibility, shear strength and mass density. Main results are presented and discussed.

International Journal of Impact Engineering, 2015

This paper presents an experimental and numerical study on the penetration of granular materials by small-arms bullets. In the experimental tests, five different types of granular material (0-2 mm wet sand, 0-2 mm dry sand, 2-8 mm gravel, 8-16 mm crushed stone and 16-22 mm crushed rock) were impacted by four different types of smallarms bullets (7.62 mm Ball with a soft lead core, 7.62 mm AP with a hard steel core, 12.7 mm Ball with a soft steel core and 12.7 mm AP with a tungsten carbide core). The tests were carried out using different rifles to fire the projectiles, while the granular materials were randomly packed in a 320 mm diameter specially-designed steel tube. In all tests, the initial projectile velocity and the depth of penetration in the granular material were measured for each bullet type. In the numerical simulations, a discrete particle-based approach was used to model the behaviour of sand during bullet impact. The method works with discrete particles that transfer forces between each other through contact and elastic collisions, allowing for a simple and robust treatment of the interaction between the sand particles and the bullet which is represented by finite elements. An important observation from the study is that the penetration depth in dry sand is strongly influenced by deviation of the bullet from its original trajectory. Good agreement between the available experimental results and the numerical predictions is also in general obtained.

2017

Objectives: In accordance with the Munitions Response Program of the Exploratory Development of the Strategic Environmental Research and Development Program (SERDP) (i.e., MRSEED-16-01), the objectives of the present study are to: • Quantify statistical penetration depths through explicit numerical simulations of projectile penetration for a variety of soil types, moisture contents, and impact conditions; X

1976

Experimental Mechanics, 2008

The time and depth of vertical one-dimensional projectile penetration into sandy media in the near shore region are derived. A precise definition for the physical properties and for the behavior of the sandy medium following the projectile impact are evaluated. Three separate time intervals following projectile impact are identified. During the first 3 ms of penetration, the deviatoric friction stress is shown to be negligible and the integrated Mie-Grüneisen equation of state (or, equivalently, the Hugoniot-adiabat) may be applied to compute the normal penetration resistance force from the sand pressure. In order to compute sand pressure as a function of the sand density D by the integrated Mie-Grüneisen equation of state, the Mie-Grüneisen dimensionless constants γ 0 and s and the dimensional speed of sound C 0 in the sandy medium are required. In order to illustrate the onedimensional shock wave propagation in both wet and dry sands, Hugoniot data for wet and dry silica sands are evaluated by a three degrees of freedom algorithm to compute these required constants. The numerical results demonstrate that the amplitude of the shock wave pressure in the wet silica sand (41% porosity) is approximately onethird of the shock wave pressure amplitudes in the dry silica sands (22% and 41% porosity). In addition, the shock wave pressure dampens quicker in the wet sand than in the dry sands.

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