ANALYSIS OF LONG RODS IMPACTING CERAMIC TARGETS AT HIGH-VELOCITY

This paper presents an analysis of recently reported experimental data on penetration of semi-infinite ceramic and metal targets by long rod s at relatively high velocity (up to 4,500 m/s). Data examined were fo r pure tungsten rods having length-to-diameter ratios of 15 and 20. Th e rods were impacted by confined aluminum nitride (AlN), alumina (Al2O 3), and a metal target of aluminum in reverse ballistic tests. Penetra tion rates were reported to be essentially constant throughout the pen etration process at all impact velocities considered. Further, depths of penetration characterized as ''primary penetration'' agreed with ex pected levels based on measured penetration rates and rod erosion rate s. However, above an impact velocity of about 2,000 m/s, considerably more penetration was observed in ALN and aluminum targets. In this eff ort, established techniques were used to treat penetration into semi-i nfinite ceramic, to include the high initial strength of the ceramic a nd its degradation, in time, through time-dependent damage mechanisms. The model results agreed with reported primary penetrations for AlN a nd aluminum targets. Further, additional ''secondary penetration'' by the rod erosion products at these high impact velocities was explored. The paper includes detailed descriptions of the analysis and some phy sical interpretations for the observations.