Ballistic performance of graphite/epoxy and S2-glass/epoxy composites with polycarbonate facing

Ballistic impact testing was carried out on 12" X 12" panels of both S-2 glass/epoxy system and graphite/epoxy laminate. S2-glass/epoxy laminates of three thicknesses made of four, six and eight-layers of twill weave fabric were used 'with' and 'without' polycarbonate facing. Two thicknesses (2.54 and 3.17 mm) of polycarbonate were used. Three thicknesses of quasi-isotropic graphite/epoxy laminates (made sixteen, thirty-two, and forty,eight Unidirectional plies) were used with polycarbonate facings of three (1, 3.175 and 4.3 mm.) thicknesses. The laminates were subjected to ballistic loading using a 30-caliber sabo-assisted projectile. Both the striking velocity and exit velocity were measured using magnetic sensors. The energy absorbed and the ballistic limit for each specimen was calculated using the principle of conservation of momentum. The Florence model was adopted in making theoretical predictions for the absorbed energy and the ballistic limit. Post-impact assessment of through, the thickness damage was conducted using ultrasonic pulse-echo immersion C-scan technique. A three-dimensional transient finite element code DYNA-3D was used to simulate the ballistic impact loading for S2-glass/epoxy laminates 'with' and 'without' polycarbonate facing. From this simulation, absorbed energy and ballistic limit were determined.