Ballistic Response of Woven Kevlar Fabric as a Function of Projectile Sharpness

Right circular cylinders (RCC) are a common fragment-simulating projectile used to simulate debris resulting from an improvised explosive device (IED) blast. The specifications for ballistic performance of soft body armor specify the geometry and mass of RCC projectiles used for testing. The edges on the impacting side of an RCC projectile have a fillet radius, and recent investigations indicate that the fillet radius (or “sharpness”) of the projectile may affect the ballistic limit velocity, V50. It is hypothesized that this happens because the sharpness of the projectile changes the fiber failure mechanism, so to test this, 4 gr RCC projectiles with varying fillet radii (0.64 mm, 1.27 mm and 1.70 mm) are precisely manufactured. Previously collected, unpublished data for 4 gr RCC projectiles with fillet radii of 0.10 mm, 0.18 mm and 0.25 mm are also included to assess a range of projectile sharpness values. Ballistic impact tests on single layer woven Kevlar K706 fabric are conducted using a laboratory gas gun to measure the limit velocity, and it is found that the limit velocity decreases with increasing fillet radii. Back surface images and impacted targets are examined post-mortem to identify failure mechanisms.