Empirical Ballistic Limit Velocity Model for Bi-Layer Ceramic–Metal Armor

Abstract

An empirical model to estimate the ballistic velocity limit (BLV) of bi-layer ceramic–metal armor materials, considering momentum and energy balance during impact process, is proposed. Three ceramic materials as front layer, namely: alumina (Al2O3 96%) boron carbide (B4C) and silicon carbide (SiC) and three materials as backing layer, namely: aluminium alloy (Al 5083H116), steel 4340 and titanium alloy (Ti6Al4V), are considered. Initially, materials constitutive and failure model constants are validated through comparison of simulations performed using finite element explicit solver, AUTODYN®, against the available experimental data in the literature. Impact simulations of different combinations of thicknesses and materials from three ceramic materials and three metal materials and thicknesses and different projectile lengths, chosen based on orthogonal array technique, are performed from which B LV of the armors are calculated. Empirical constants in the proposed model are obtained using least square fitting to the B LV data obtained from simulations. Comparison between results obtained from the empirical model for B LV of ceramic–metal armor impacted by flat-ended projectiles, with available limited experimental data is carried out. The empirical B LV expression is used for optimization of alumina/aluminium armor system, for weight and volume objectives. Optimization results compare well with the experimental measurements.