Influence of side-impacting dynamic armour components on long rod projectiles

Using add-on armour components to disturb long rod projectiles (LRP) before they hit the basic armour is a weight efficient way of increasing the protection of lighter vehicles. In this study, the effect of moving armour components, in the form of one or three cylindrical rods, hitting the side of the LRP, was investigated. The rods were hitting the side of the LRP at an angle of attack of 60 degrees. Rod velocities of 200 and 600 m/s and hitting points in the front and in the middle of the LRP were studied. The velocity of the LRP was 2000 m/s. The study is based on small scale reverse impact experiments and continuum dynamic simulations. To fragment the LRP, high rod velocities were needed. One rod hitting the LRP at 200 m/s gives approximately the same effect (some yaw but no fracture) as that of a moving oblique plate having the same velocity and angle of obliquity. Increasing the velocity of the rod to 600 m/s resulted in fracture of the LRP closely behind the hitting point both when hitting the front and the middle of the LRP. To obtain fracture of the LRP using plates the direction of the plate movement has to be changed (same direction as the projectile). The experiments with three rods were carried out to obtain multiple fractures but this did not occur. The reason for this is under investigation. Continuum dynamic simulations using new material models and parameters have reasonably successfully reproduced the experimental results giving us a numerical tool to study fracture of LRP.