Multi-hit Performance of Small Arms Protective Armor

The weight tolerance and value of various US Army assets dictates the sophistication of the armor systems employed for their protection.  The Warfighter is the most weight sensitive and highest value of all assets and thereby utilizes the most advanced and expensive materials in their protection systems.  This effort provides a significant improvement in understanding the multi-hit behavior of advanced ceramic-based hard body armor and similar armor systems through careful implementation of ballistic experiments and the development of computational tools for prediction of multi-hit impacts in this type of armor system.  A standard methodology for deriving the constituent constants for the Johnson-Holmquist-Beissel (JHB) Material Model was devised and demonstrated on Pressure Assisted Densification boron carbide (PAD B4C) ceramic.  Statistical fractographic analysis was also carried out on micro-CT scans of ballistically interrogated ceramic.  The damage was then compared with the computationally derived prediction and the energy absorption of the conditioned targets.  This enables correlation between the damaged area and the degradation of ballistic capability as a result of the associated damage.  This white paper details the results from Phase I and Phase II and the plan for the Sequential Phase II (SP2) proposal that will outline the path to complete predictive computations into advanced body armor, aircraft armor, spall liners, C-kits, and other advanced armor systems. The focus for the SP2 will be on predictive capability with the other predominate material that constitutes advanced aircraft and body armor systems, Ultra High Molecular Weight Polyethylene (UHMWPE).  The goal will be to complete an end-to-end modeling process where armor designers, engineers and scientists can: Predict armor performance of a first impact on an advanced armor component Predict armor performance of multiple impacts at a specified distance from the first impact (within the damage interaction zone) Quantify the degradation in ballistic efficiency of brittle armors systems (ceramic armor or transparent armor) using statistical fractographic analysis of damaged regions.