Analysis of long rods impacting ceramic targets at high velocity

Abstract

This paper presents an analysis of recently reported experimental data on penetration of semi-infinite ceramic and metal targets by long rods at relatively high velocity (up to 4,500 m/s). Data examined were for pure tungsten rods having length-to-diameter ratios of 15 and 20. The rods were impacted by confined aluminum nitride (AIN), alumina (Al 2O 3), and a metal target of aluminum in reverse ballistic tests. Penetration rates were reported to be essentially constant throughout the penetration process at all impact velocities considered. Further, depths of penetration characterized as “primary penetration” agreed with expected levels based on measured penetration rates and rod erosion rates. However, above an impact velocity of about 2,000 m/s, considerably more penetration was observed in AIN and aluminum targets. In this effort, established techniques were used to treat penetration into semi-infinite ceramic, to include the high initial strength of the ceramic and its degradation, in time, through time-dependent damage mechanisms. The model results agreed with reported primary penetrations for AIN and 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 physical interpretations for the observations.