Micro-mechanismof multiscale dynamic fracture

The shock propagation in non-uniform medium is studied theoretically and experimentally. A set of experiments on shock loading of high-strength low-alloyed AB2 steel is performed. The “trigger” mechanism for switching the dynamic fracture from one scale to another is shown to be the resonance interaction of plastic flow oscillations and mesoscopic structural elements. There is a threshold strain rate at which the defect (decrease) of mass velocity at the plateau of compressive pulse increases abruptly. Under strain rates higher threshold value, a multitude of short transcrystalline cracks is formed, which results in decay of shock wave.