Threshold Regimes and Micromechanisms of Dynamic Straining

Two conditions for resonance interaction of loading stress pulse and polarized dislocation structure are found: (1) equality of space period of the dislocation structure and space period of shock front, (2) equality of local strain rate at the mesoscale and macroscopic strain rate. Shock tests of D16 aluminum alloy within impact velocity range of 30-450 m/s have shown that maximum dynamic strength is realized when both above conditions for resonance interaction are fulfilled simultaneously, which occurs at the impact velocity of 382m/s. The resonance interaction results in formation of deformation structures of mesoscopic scale revealed with metallographic techniques and X-ray analysis of post shocked specimens.