Numerical simulation of a sample recovery fixture for high velocity impact: Studies at various impact velocities.

摘要

Numerical results are presented for a model of the sample recovery fixture developed by Sawaoka to preserve powder samples subjected to high velocity impact. These results were obtained with the hydrocode CSQ, for an axisymmetric stainless steel recovery fixture which approximates the actual fixture. Results are presented for stainless steel impactors with impact velocities of 0.9, 1.3, 1.6, 1.9 and 2.5 km/sec, corresponding to typical velocities for a series of experiments. The results obtained for an impact velocity of 0.9 km/sec are used to illustrate focusing effects in rutile powder compacts. After impact, a planar shock wave propagates through the fixture until it reaches the rutile sample. Because the shock velocity is slower in the powder compact, the wave fronts outside the sample radius propagate at a faster speed than those inside the sample. This results in a radial pressure gradient at the edge of the rutile sample. For the 0.9 km/sec impact velocity case, the radial pressure gradient generates wave fronts at the edge of the sample that are almost parallel to the axial direction. The radial effects are the dominant features and account for pressures and temperatures much higher than those predicted by a one dimensional analysis. 5 refs., 4 figs.