POWDERED MATERIAL FLOW IN THE SHOCK-WAVE BRANCHING REGION

The foil method and metallographic studies of powdered material partic le orientation in specimens subjected to loading are used to show that upon regular reflection of colliding shock waves the flow in the regi on where they branch is homogeneous. A well expressed high-speed flow of material behind the Mach wavefront exists for irregular reflections . In the shock wave branching region, two qualitatively different flow regimes are possible: without high-speed flow slippage, and with such slippage. Flow without slippage is Sound at shock wave amplitudes belo w same threshold value, dependent on the initial density of the powder ed metal. A transition zone in the form of a viscous wake exists at th e boundary of the high-speed and low-speed flows. A numerical solution of the model problem of mixing of two homogeneous flows of viscous li quid was carried our. By comparing calculation results to experiments which recorded characteristic viscous wake parameters, it was establis hed that the effective viscosity of a shock-compressed copper powder w ith dispersion less than or equal to 60 mu m comprises similar to 0.01 m(2)/sec, with the material remaining in the solid state at a density close to that of a monolithic specimen.