Impact fragmentation of aluminum reactive materials
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Authors
Hooper, J.P.
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Date of Issue
2012
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Abstract
We report the fragmentation of brittle, granular aluminum spheres following high velocity impact
(0.5-2.0 km/s) on thin steel plates. These spheres, machined from isostatically pressed aluminum
powder, represent a prototypical metallic reactive material. The fragments generated by the impacts
are collected in a soft-catch apparatus and analyzed down to a length scale of 44
l
m. With increasing
velocity, there is a transition from an exponential Poisson-process fragment distribution with a
characteristic length scale to a power-law behavior indicative of scale-invariance. A normalized
power-law distribution with a finite size cutoff is introduced and used to analyze the number and
mass distributions of the recovered fragments. At high impact velocities, the power-law behavior
dominates the distribution and the power-law exponent is identical to the universal value for brittle
fragmentation discussed in recent works. The length scale at which the power-law behavior decays is
consistent with the idea that the length of side microbranches or damage zones from primary cracks
is governing this cutoff. The transition in fragment distribution at high strain-rates also implies
a significant increase in small fragments that can rapidly combust in an ambient atmosphere.
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Article
Description
The article of record as published may be found at http://dx.doi.org/10.1063/1.4746788
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Physics
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Citation
J. P. Hooper. "Impact fragmentation of aluminum reactive materials." J. Appl. Phys. 112, 043508 (2012).
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.