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

Right circular cylinders RCCs 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. Furthermore, the edges on the impacting side of an RCC projectile have a fillet radius, and recent investigations indicate the fillet radius or sharpness of the projectile may affect the ballistic limit velocity or 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 0.635 mm, 1.270 mm, and 1.702 mm are precisely manufactured. Previously collected, unpublished data for 4-gr RCC projectiles with fillet radii of 0.102 mm, 0.178 mm, and 0.254 mm are also included to assess a range of projectile-sharpness values.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 V50, which is found to decrease with increasing fillet radii. Impacted specimens are inspected to understand the different failure mechanisms dependent on fillet radius.