Experimentation and modeling of inclined ballistic impact in thick polycarbonate plates

The penetration and perforation of a thick polycarbonate (PC) plate (one and 3 stacked) by an armor piercing 7.62 mm projectile is investigated experimentally and numerically. The characteristic structure of the projectile’s trajectory in the PC plates is studied. It is observed that the trajectory consist of a cavity and a circumferential cracked zone attached to it, which is fully embedded within a cylindrical plastic zone. The size of the plastic zone is approximately twice that of the cavity zone and can be clearly observed due to the change of the refractive properties of the material. Strong local recovery of the PC is shown as well. A 3D transient non-linear adiabatic finite element simulation is performed using the commercial software Abaqus 6.9-EF1. The numerical analyses include two combined failure criteria: “Ductile failure with damage evolution”, and tensile failure. The material properties are strain rate and temperature dependent. The numerical simulations are tested by comparing the numerical trajectory prediction to actual trajectories of inclined impacts of projectiles. It is found that the projectile perforates the plate at angles of inclinations of 30° and higher. The observed agreement between experiments and numerical modeling indicates that the combined effect of the two failure criteria (tensile vs. ductile failure) can reasonably well predict the projectile’s trajectory within a thick PC plate. The numerical analyses are further used to study the effect of the projectile impact velocity on the depth of penetration (DOP). It is found that the DOP scales slightly non-linear with the impact velocity. The core velocity during the penetration process is also slightly non-linear. The deceleration during penetration is almost a linear function of the penetration velocity and it is higher for higher penetration velocities.