On the correlation between multiscale mechanisms of deformation in uniaxial dynamic straining and high velocity penetration

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.