Shear thickening fluid impregnated ballistic fabric composites for shock wave mitigation

This study reports on the shock wave protective performance of woven Twaron fabric impregnated with shear thickening fluid (STF). The STF was prepared from a combination of mechanical and ultrasonic mixing of fumed silica nanoparticles dispersed in liquid polyethylene glycol (PEG) polymer. The shear thickening characteristics were determined from rheological tests. Two shock wave parameters governing blast related injuries are used to evaluate the performance of the STF treated fabrics - peak pressure and rate of pressure rise. The results of our shock tube tests demonstrate that the STF treated fabric composites offer superior shock wave protection as compared to untreated (neat) fabric and fabric impregnated with PEG only. After STF treatment, the normalised average peak pressure amplification is significantly reduced from 2.46 to 1.49 while the attenuation in normalised maximum rate of pressure rise is even more pronounced - from 2.3 to 0.76. Apparent material density is found to correlate with the average peak pressure and maximum rate of pressure rise. This implies that the density increases enough to increase the equilibrium sound speed in the fabric, and therefore preclude the formation of shock wave in the fabric. Ballistic tests using steel projectiles were also conducted to check that the STF treated fabrics continued to enhance ballistic protection as reported by other researchers. Overall, the results show that the STF treated fabrics have potential applications not only for ballistic protection but also for shock wave mitigation.