Honeycomb in hybrid composite armor resisting dynamic impact

Abstract

Behind Armor Blunt Trauma (BABT) is an emerging problem in body armor due to excessive deformation resulting from projectile impact. A potential to reduce BABT has been identified by incorporating a honeycomb layer in a Hybrid Composite Armor (HCA). Honeycombs along with other cellular solids have been used primarily for low velocity impact absorption and in some cases for vehicle mounted armor. Their role in body armor remains unexplored and is the focus of this study. A new HCA with aluminum honeycomb was designed and evaluated using ballistic testing in compliance with the level III NIJ 0101.06 body armor standard. Performance improvement of the armor was verified from these tests using Back Face Signature (BFS) and V50 metrics. Effects of honeycomb attributes on ballistic performance were successfully correlated using an analytical scheme that showed good agreement with the experimental results. HCA was found to qualify for the standard, while demonstrating a maximum BFS reduction of 40.8% (and hence BABT) in comparison to a baseline of the same weight. Limitations to the use of honeycombs in armor were also identified. Performance benefits of honeycomb inclusion in armor observed experimentally were supplemented by numerically derived results from FEA in ABAQUS®. This HCA design has the highest known propensity to reduce injury both due to the light weight and improved trauma performance compared to existing designs. A selection methodology was demonstrated to further extend this advantage by inclusion of other commercially available honeycombs.