Ballistic impact and explosive blast resistance of stitched composites

The effectiveness of stitching in increasing the damage resistance of polym er composites against ballistic projectiles and explosive blasts is determi ned. Glass-reinforced vinyl ester composites stitched in the through-thickn ess direction with thin Kevlar (R) -49 yarn were impacted with a bullet tra velling at 0.9 km s(-1) or an underwater explosive shock wave moving at 1.5 km s(-1). The amount of delamination damage to the composite caused by a b allistic projectile was reduced slightly with stitching. Stitching was high ly effective in increasing the damage resistance against explosive blast lo ading. The increased damage resistance was due to the stitching raising the Mode I interlaminar fracture toughness of the composite. While the stitche d composites experienced slightly less damage, their flexural modulus and s trength was similar to the properties of the unstitched composite after bal listic impact testing. The post-blast flexural properties of the stitched c omposites, on the other hand, were degraded less than the properties of the unstitched material. (C) 2001 Published by Elsevier Science Ltd.