Experimental Analysis of Penetration into Targets Made of Kevlar Laminate with STF Fluids

In this paper, the ballistic performance of Kevlar plain-woven fabric impregnated with a colloidal shear thickening fluid (STF) is investigated. STF is composed of silicon dioxide nanoparticles and polyethylene glycol and is a non-newtonian fluid behavior defines as the increase of viscosity with the increase in the applied shear rate. The ballistic limit and specific ballistic energy of double and quadruple ply fabric systems impregnated with 15, 25 and 35 wt% STF particle concentration are compared to neat fabric. Results show those targets with 35 wt% STF particle concentration yield the highest ballistic limit for double and quadruple ply fabric. The double ply system with 35 wt% STF particle concentration showed the greatest improvement in specific ballistic energy over neat double ply systems. High speed photography showed that the neat Kevlar experience more localized deformation on impact. A finite element model was created using Ls-Dyna software and it was shown that the increased ballistic performance for shear thickening fluid impregnated Kevlar fabric is at least due to the increased friction between projectile and target.