Experimental research of shear thickening fluid (STF) impregnated S2 glass fiber fabrics puncture resistance

The aim of this study is to prepare shear thickening fluid (STF) impregnated S2 glass fiber fabrics for soft body armor applications and to experimentally investigate their puncture resistance. In this study, the puncture resistance of fluid-impregnated S2 glass fiber fabrics showing shear thickening was compared with the puncture resistance of dry S2 glass fiber fabrics using two different test methods drop weight test and quasi-static drilling test. In this study, besides analyzing the rheological behavior of Shear Thickening Fluid (STF) containing 20% by weight of fumed silica, STF impregnated S2 glass fiber fabrics were prepared and the mechanical properties of these fabrics were experimentally investigated in terms of their puncture resistance. Before the tests, STF was prepared by mixing fumed silica and polyethylene glycol using a mechanical stirrer and then keeping this suspension in an ultrasonic bath. Drop weight puncture and quasi-static puncture tests of STF impregnated S2 glass fiber fabrics were performed using a drill bit mounted on the mechanism. The rheological data of the shear thickening fluid (STF) containing 20% by weight of fumed silica showed a sudden increase in viscosity at the critical shear rate. While the maximum viscosity value was observed as 463 Pa.s, the critical shear value was obtained as 2 1/s. According to the drop weight test results, the penetration depth into the backing material is 17.57 mm, 34.24 mm, and 51.94 mm, respectively, for the conditions where the penetrator tip is dropped from a height of 200 mm, 300 mm and 400 mm in STF impregnated fabrics. In dry fabrics, the penetrating depth of the base material is 25.37 mm, 41.63 mm and 65.49 mm, respectively, for the conditions where the piercing tip is dropped from a height of 200 mm, 300 mm and 400 mm. In STF-impregnated fabrics, for the conditions where the piercing tip is dropped from a height of 200 mm, 300 mm and 400 mm, the trace width formed on the backing material is 17.81 mm, 29.31 mm and 24.79 mm, respectively. In dry fabrics, for the conditions where the penetrator tip is dropped from a height of 200 mm, 300 mm and 400 mm, the track width created on the backing material is 11.63 mm, 16.28 mm and 18.95 mm, respectively. According to the quasi-static drilling test results, the piercing force is 0.15 kN for STF-impregnated fabrics and 0.12 kN for dry fabrics when the piercing tip sinks 40mm into the backing material.