Thickness Effect on Cross-Ply GLARE 5 FML Beams Subjected to Ballistic Impact

In this study, GLARE 5 fiber-metal laminates (FMLs) of dimensions: 254mm25.4mm (10″×1″) with various thicknesses were impacted by a 0.22 caliber bullet shaped projectile using a high-speed gas gun. The specimens were cut transversely through the impact center using a diamond blade cutting wheel for destructive damage evaluation. The results showed that failure pattern was changed as the specimen thickness increased. This was very obvious especially for (5/4) and (6/5) configurations. In addition, a high-speed camera was used to record the damage evolution on the non-impacted side of the specimens. It was found that when impacted ballistically by the same projectile velocity, debonding between the bottom (non-impacted side) aluminum layer and its adjacent glass-fiber reinforced epoxy layer was increased by changing the lay-up configuration from (6/5) to (5/4). This phenomenon was demonstrated experimentally using the video footage obtained from the high-speed camera.