Ballistic performance of p -aramid fabrics impregnated with shear thickening fluid; Part I – Effect of laminating sequence

The objective of this research was to characterize the ballistic performance of p-aramid fabrics impregnated with shear thickening fluid (STF) focusing on the laminating sequence of the layers. A panel of all neat Kevlar fabrics and two hybrid panels of neat and STF impregnated Kevlar fabrics were tested against 9 mm bullets at 436 m/s for body armor application. When the STF impregnated fabrics were laminated behind the neat Kevlar layers (N/S-panel), the backface signature decreased compared to the panel of all neat fabrics (N-panel) and the hybrid panel with neat Kevlar layers placed on the backside of the panel (S/N-panel). The enhanced ballistic performance of the N/S-panel was assumed to be due to the synchronized (or coupled) elongation of the facing yarns in the frontal layers and those in the following rear layers during the impact. Analysis was carried out, by adapting the method of accumulating successive line segments, to present the energy dissipation route of each panel during the impact.