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ABSTRACT: We conducted an experimental and analytical study to better understand the mechanisms and dominant parameters for 7.62mm
APM2 bullets that perforate 7075-T651 aluminum armor plates. The 7.62-mm-diameter, 10.7g, APM2 bullet consists of a brass
jacket, lead filler, and a 5.25g, ogive-nose, hard steel core. The brass and lead were stripped from the APM2 bullets by
the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel cores. These projectiles
were fired from a rifle to striking velocities between 600 and 1,100m/s. Targets were 20 and 40-mm-thick, where the 40-mm-thick
targets were made up of layered 20-mm-thick plates in contact with each other. The measured ballistic-limit velocities for
the APM2 bullets were 1% and 8% smaller than that for the hard steel cores for the 20 and 40-mm-thick targets, respectively.
Thus, the brass jacket and lead filler had a relatively small effect on the perforation process. Predictions from a cylindrical
cavity-expansion model for the hard steel core projectiles are shown to be in good agreement with measured ballistic-limit
and residual velocity data. The results of this study complement our previous paper with 5083-H116 aluminum target plates
in that the ultimate tensile strength of 7075-T651 is about 1.8 times greater than that of 5083-H116. We also present a scaling
law that shows a square root relationship between ballistic-limit velocity and plate thickness and material strength.
KeywordsAluminum armor plates-7.62mm APM2 bullets-Experimental study-Perforation equations-Validation
Experimental Mechanics 04/2012; 50(8):1245-1251. · 1.52 Impact Factor
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ABSTRACT: We present equations that show the effect of radial inertia for incompressible samples that are in dynamic force equilibrium
during the split Hopkinson pressure bar test or Kolsky bar test. For steel samples the radial inertia effect can be neglected;
however, radial inertia can be important for very soft materials.
KeywordsKolsky bar-Radial inertia-Incompressible soft materials
Experimental Mechanics 04/2012; 50(8):1253-1255. · 1.52 Impact Factor
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ABSTRACT: We conducted an experimental and analytical study to understand the mechanisms and dominant parameters for ogive-nose rods
and 7.62mm APM2 bullets that perforate 5083-H116 aluminum armor plates. The 20-mm-diameter, 95-mm-long, ogive-nose, 197g,
hard steel rods were launched with a gas gun to striking velocities between 230–370m/s. The 7.62-mm-diameter, 10.7g, APM2
bullet consists of a brass jacket, lead filler, and a 5.25g, ogive-nose, hard steel core. The brass and lead were stripped
from the APM2 bullets by the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel
cores. These projectiles were fired from a rifle to striking velocities between 480–950m/s. Targets were 20, 40, and 60-mm-thick,
where the 40 and 60-mm-thick targets were made up of layered 20-mm-thick plates in contact with each other. The measured ballistic-limit
velocities for the APM2 bullets were 4, 6, and 12% smaller than that for the hard steel cores for the 20, 40, and 60-mm-thick
targets, respectively. Thus, the brass jacket and lead filler had a relatively small effect on the perforation process. In
addition, we conducted large strain, compression tests on the 5083-H116 aluminum plate material for input to perforation equations
derived from a cavity-expansion model for the ogive-nose rods and steel core projectiles. Predictions for the rod and hard
steel core projectiles are shown to be in good agreement with measured ballistic-limit and residual velocity data. These experimental
results and perforation equations display the dominant problem parameters.
KeywordsAluminum armor plates-Ogive-nose rods-7.62mm APM2 bullets-Experimental study-Perforation equations
Experimental Mechanics 04/2012; 50(7):969-978. · 1.52 Impact Factor
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ABSTRACT: A 50/20-mm, two-stage, light-gas gun launched spherical-nose steel projectiles with 7.1-mm-diameter and 39.1-mm-length to an impact velocity of 3.0 km/s. The projectiles penetrated 115-mm-diameter, simulated geological targets with density of 1700 kg/m/sup 3/ that consisted of several grades of sand and a binder. We experimented at normal impacts (theta = 0 degrees) and at oblique impacts (theta = 60 degrees). In-material x-ray photographs at three penetration depths showed the depth, length of eroded rod, and cavity shape. We compared penetration depth vs time data and rod-length vs time data with Tate's eroding rod model and found excellent correlation between measured and predicted results. We also developed approximation closed-form equations for Tate's model from a perturbation analysis. Predictions from the closed-form equations also showed good correlation with measurements. 13 refs., 3 figs., 1 tab.
12/1987
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ABSTRACT: Perforation experiments were conducted with 26.3 mm thick, 6061-T651 aluminum plates and 12.9 mm diameter, 88.9 mm long, 4340 Rc = 44 ogive-nose steel rods. For normal and oblique impacts with striking velocities between 280 and 860 m/s, we measured residual velocities and displayed the perforation process with X-ray photographs. These photographs clearly showed the time-resolved projectile kinematics and permanent deformations. In addition, we developed perforation equations that accurately predict the ballistic limit and residual velocities.
International Journal of Impact Engineering.
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ABSTRACT: A series of 26 terminal ballistics experiments was performed to measure the penetration of simple confined aluminum nitride targets by a long tungsten rod. Impact velocities ranged from 1.5 to about 4.5 km/s. The experiments were performed in the reverse ballistic mode using a two-stage light-gas gun. Penetrator diameter, D, was 0.762 mm (0.030 in). The length-to-diameter ratio for the penetrator was for nearly all the tests and never less than . Primary instrumentation for these experiments was four independently timed, 450 kV flash X-rays. These X-rays provided four views of the penetrator-target interaction during the penetration event from which the following data were determined: p = penetration depth as a function of time, Lr = remaining length of penetrator as a function of time, as well as final penetration depth, target hole geometry, spatial distribution of the eroded rod material, etc. From these data, = speed of penetration into the target and of “consumption” of the long rod were obtained.
International Journal of Impact Engineering.
