Energy Absorption of Nano-Reinforced and Sandwich Composites in Ballistic and Low-Velocity Punch-Shear

This paper presents an investigation on energy absorption characteristics of nano-reinforced panels, laminated face sheets and sandwich composites in high velocity ballistic and low velocity punch-shear experiments. The vinyl ester panels were reinforced with 1.25 and 2.5 wt. percent nanoclay and exfoliated graphite platelets. Three different face sheets were manufactured with E-glass, Owens Corning HP ShieldStrand glass and T-700 Carbon woven fabric in vinyl ester; and one with the E-glass and graphite platelets impregnated vinyl ester matrix. The sandwich composites were fabricated with balsa, PVC foam, 3-D fiber reinforced Tycor and fire resistant fly-ash based Eco-Core cores in between E-glass/vinyl ester face sheets. Ballistic tests were conducted according to NIJ level III using a universal receiver equipped with a barrel to launch 0.308 caliber M80 ball round projectile at about 890 m/s. Low velocity punch-shear tests were performed at around 3 m/s according to ASTM D3763 Standard using a drop-weight impact test system. The tortuosity of the fractured surface in nanocomposite specimens has been investigated using digital microscope. In ballistic tests, the 3-D fiber reinforced Tycor core provided the most resistance when projectile strikes at the web-flange interface region. The 2.5 wt. pct. graphite platelet reinforced nanocomposite, HP ShieldStrand glass vinyl ester face sheets, and E-glass/Eco-Core sandwich composite showed the best energy absorption under low velocity punch-shear.