Study of mechanical property of shear thickening fluid (STF) for soft body-armor

Abstract STFs have been widely used for soft body-armor because of STF reversible and repeatable thickening characteristics. However, shear thickening mechanism characterized by rheological properties cannot well explain thickening mechanism of STF against the penetrations and impacts. In this study, a cycle experiment of quasi-static squeeze and pull-out of STF by metal rod were carried out on the INSTRON. Effects of velocity, interface condition and boundary et al were discussed. Typical displacement-load curves show that STF thicken in the normal load when the rate reach critical value. Taking a pull-out experiment as example, force without thickening of STF is a constant value, about 1.5 N. The maximum force with thickening of STF is about 150 N, which increases 100 times due to the thickening of STF. A simple simulation of clustering behavior of nano-particles in STFs in the squeeze process is depicted. The experiment and simulation studies have proved that SiO 2 nano-particles in STF will rearranged to cause a jammed zone in the normal load.