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In order to identify the successive stages of developing the hierarchy of multiscale
mechanisms of dynamic straining, the shock-induced mesostructure formation is studied in
combined experiments. Shock tests of two kinds of aluminum alloy, 1561 and 1565 alloys
were conducted in parallel in two regimes of loading: (i) under uniaxial strain conditions and
(ii) in high velocity penetration. Combination of loading regimes allows the correlation in
formation of multiscale structure depending on strain rate and scheme of shock loading to be
traced for both alloys. Formation of mesoscale-1 (1-10 µm) is initiated by the particle velocity
pulsations resulted from space polarization of dislocation structure.
In 1561 aluminum alloy the structural elements of mesoscale-2 (50-150 µm) are the result of
grouping the microshears, whereas in 1565 alloy the mesostructure is the fault formations
localized near the boundary of penetration cavern. The strength behavior of both kinds of
aluminum alloy proves to be opposite - when resistance to penetration increases, the spall
strength decreases.
Keywords: : shock loading, multiscale dynamic deformation, high velocity penetration, structural instability, spallation |
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