Abstract
We characterize spall damage in shock-recovered ultrapure Al with metallography and x-ray tomography. The measured damage profiles in ultrapure Al induced by planar impact at different shock strengths, can be described with a Gaussian function, and showed dependence on shock strengths. Optical metallography is reasonably accurate for damage profile measurements, and agrees within 10–25% with x-ray tomography. Full tomography analysis showed that void size distributions followed a power law with an exponent of γ = 1.5 ± 2.0, which is likely due to void nucleation and growth, and the exponent is considerably smaller than the predictions from percolation models.
Highlights
Damage of ductile metals under high strain rate loading has long been studied with planar shock loading
Full tomography analysis showed that void size distributions followed a power law with an exponent of γ = 1.5 ± 2.0, which is likely due to void nucleation and growth, and the exponent is considerably smaller than the predictions from percolation models
The soft-recovered samples were examined with 2D metallography and 3D x-ray tomography, and results are shown in Figs. 2–6 and Table I
Summary
Damage of ductile metals under high strain rate loading has long been studied with planar shock loading. Void nucleation and growth coupled with plasticity, are responsible for shock-induced spallation damage, and such information is extremely useful for developing physics-based, dynamic damage models.[1,2,3,4,5] in situ, real time measurements are largely limited to free surface or target-window interface velocities, since the technical challenges still render such measurements a formidable task on void evolution in ductile metals. Damage characterization has heavily relied on shock-recovered samples, which are normally examined with optical metallography, scanning and transmission electron microscopy, and electron backscattered diffraction.[6,7,8,9,10] These techniques are mostly two-dimensional (2D) in nature, and one has to resort to serial sectioning, or stereographic techniques such as the Schwartz-Saltykov method, to obtain 3D information.[11,12,13,14,15] C Author(s) 2014
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