Development of stab resistant armor for different energy levels using shear thickening fluid reinforced multi-layered p-aramid fabrics

Stab-resistant armors are important protective gear for the law enforcement officers and security forces. This research attempts to develop stab-resistant armors for different impact energy levels using multi-layer neat and shear thickening fluid (STF)- treated Kevlar (R) (R) fabrics. The developed panels were tested using National Institute of Justice's (NIJ) P1 knife at wide range of stabbing energy from 6 to 36 J. The panel containing 16 layers of STF-treated Kevlar (R) (R) fabric met the requirements at normal and over-test conditions showing penetration depth lower than 7 and 20 mm, respectively. For stabbing at high energy level (>= 24 J), the effect of number of Kevlar (R) (R) fabric layers was found to be highly beneficial in case of STF-treated condition and not so for the neat one. STF treatment reduced the stab penetration depth by 40%-68% at 24-36 J energy level without any increase in effective weight of the panel. The fabric-knife interaction was also studied using a novel sharpness tester and optical microscopy. It was found that the tip of knife deformes and sharpness declines at a faster rate in case of STF-treated fabric. The study opens up possibilities to explore other materials that would damage the tip of knife during stabbing ensuring better protection.