Ballistic Performance of Shear Thickening Fluids (STFs) Filled Paper Honeycomb Panel: Effects of Laminating Sequence and Rheological Property of STFs

In order to exploit future soft body armor to achieve a more comprehensive protection than just the torso part of the body, in this study, shear thickening fluids (STFs) with different rheological properties are fabricated by planetary mixer and three-roller mills to investigate the mixing process effect on the resultant rheological behavior. Rheological results indicate the critical shear rate and the maximum viscosity of STF are deeply influenced by the dispersion degree of nano-silica particles in PEG. These STFs are then filled into a paper honeycomb partition to prepare a STF-based protective structure. Different laminating sequences of the composite panels composed one STF structure layer and nineteen layers of Kevlar fabric are obtained by simply placing the STF structure at different positions in the composite panels. The ballistic tests are conducted according to the NIJ 0101.06—Type II standard using 9 mm Full Metal Jacketed Round Nose bullets. Our results show that the absorbed energy of the composite panel with STF that thickens at higher shear rate is higher compared to that using STF that thickens at a lower shear rate. It suggests the STF with higher critical shear rate would be optimally used in ballistic impacts. In addition, ballistic testing results confirm that the STF structure placed at the rear position can significantly contribute to the increase in impact resistance.