Dynamic fracture in carbon-fibre composites: Effect of steel and ice projectiles

In this study the resultant ballistic dynamic response observed in a 2x2 twill weave T300 carbon fibre/epoxy composite flat-plate specimen is examined, using a combination of non-invasive analysis techniques. The study investigates deformation, damage and fracture following the impacts with both solid (steel) and fragmenting (ice) projectiles travelling with velocities of 70-90 m/s and 300-500 m/s, respectively. Digital image correlation was employed to obtain displacement data for the rear surfaces of the specimens in each experiment, and used to assess the effect of impact velocity and projectile material on the specimen’s response. 3D X-ray computed tomography was used to image and visualize the resultant internal cloud of damage and fracture, initiated by dynamic loading in each specimen. It was shown that solid projectiles led to greater localized deformation and, in some cases, penetration, whereas fragmenting projectiles destroyed on impact resulted in more distributed loading leading to major front-surface damage depending on the depth on indentation before fragmentation.