Experimental analysis of the impact protection properties for Kevlar® fabrics under different orientation layers and non-Newtonian fluid compositions

Abstract

Use of colloidal silica suspensions impregnated in Kevlar® fabrics is new avant-garde of protection equipment for stab wounds and piercing objects. Kevlar® fabrics impregnated with non-Newtonian fluids have been used for protection against sharp blows, mainly due to their lightweight, good flexibility, and superior resistance properties. The aims of this investigation are to demonstrate that Kevlar® fabric impregnated with shear thickening fluids could be improved its performance through the use Aminopropyltrimethoxysilane, as well as by increasing the concentration of silica nanoparticles in its composition. Friction tests on yarns showed that Kevlar® yarns with shear thickening fluids (sample C3—25% Silica and 75%polyethylene glycol with 38% aminopropyltrimethoxysilane), presented higher strength values (10.5 N) when compared with other samples. Impact resistance tests showed that Kevlar® samples with highest concentration shear thickening fluids nanoparticles and oriented fabric layers (C3 OR) presented better performance regarding to penetration depth of stabs P1 (17 mm), S1 (18 mm) and as well as residual energy dissipation, when compared with the standard and other samples. Addition of shear thickening fluids cause reduction in the flexibility of the Kevlar® fabrics, producing sample with 42.74% less flexibility than the standard sample (C3). Adhesion tests for C3 samples exhibited more stable wettability and spreading rate, i.e., a greater adhesion of shear thickening fluids in Kevlar® fabrics than other samples due to its composition (higher concentration of nanoparticles and superior amount of silane agent). Finally, results showed that the shear thickening fluids composition as well as Kevlar® layers orientation should be used to improve the performance of Kevlar® fabrics under impact tests.

The channel flow of a real shear thickening fluid using the Lattice Boltzmann Simulation and the Theoretical Model

“…The power-law index chosen is n1=0.9 and n2=1.1 respectively. In Figure 9A, we have a velocity profile near the exit for all three cases of stress cut-off 3.72 ×10 -6 Fu/lu 2 , 4.90 ×10 -6 Fu/lu 2 and 6.28 ×10 -6 Fu/lu 2 . The analytical velocity profile was obtained using the equation for 40 and 41, and simulations are compared in Figure 9A.…”

Low-Velocity Impact Response of Auxetic Seamless Knits Combined with Non-Newtonian Fluids

“…Other authors also studied the combination of these fluids with other materials to boost their protective properties. Santos et al proved that the addition of STF to Kevlar fabrics improves the performance of these substrates under impact tests [ 17 ]. Lu et al and Santos et al also demonstrated that the combination of STF with materials like wale-knitted spacer fabrics and Kevlar woven samples, respectively, can be applied as a material for personal protection [ 18 , 19 ].…”

The channel flow of a real shear thickening fluid using the Lattice Boltzmann Simulation and the Theoretical Model

“…The shear thickening fluid (STF) impregnated high tenacity fibre is found in soft body armour application. Shear thickening behaviour is reversible, which makes the STF-treated body armour flexible yet provides strength to it [1][2][3][4][5]. A concentrated nanosized silica particle dispersed in polyethene glycol (PEG) shows the behaviour of shear thickening fluid [5][6][7][8][9][10].…”