Effect of prestressing on the ballistic performance of alumina ceramics: Experiments and modeling

In this research, the dynamic behavior of prestressed alumina tiles under ballistic impact was investigated via experiments and numerical modeling. Ballistic experiments using armor piercing (AP) rounds were conducted on tiles of different thicknesses that were subjected to confinement pressure up to 400 MPa. The ballistic experiments were conducted using a custom-built device, designed to apply biaxial compressive stress on the tiles while permitting the direct and accurate measurement of the applied pressure. The influence of both confinement pressure and tile thickness on the ballistic efficiency (BE) of the alumina tiles was measured using the depth of penetration (DOP) method. The DOP values decreased approximately linearly with increased confinement pressure, indicating an improvement in the tiles' BE. The experimental results are compared with simulations performed using a 2-D axisymmetric Lagrangian solver of finite element commercial code (LS-DYNA software). The Johnson-Holmquist ceramic model (JH2) was used to describe the behavior of the alumina. Results of the simulations correlate well with the experimentally-observed effect of decreased DOP as prestress level is increased.