Optimization of soft armor: the response of homogenous and hybrid multi-ply para-aramid and ultra-high molecular weight polyethylene fabrics under ballistic impact

This research investigated the ballistic response of homogenous and hybrid multi-ply fabrics toward developing a full-scale hybridized soft armor system. Fabrics with varying yarn and thread counts were manufactured from para-aramid and ultra-high molecular weight polyethylene yarns through a plain-woven architecture. Homogeneous fabrics used the same yarn and thread count for two- and three-ply systems. For hybrid systems, two- and three-ply stacks were assembled in various sequences including increasing and decreasing cover factor (Cfab) and varying yarn types as the strike face and rear face. Ballistic impact testing was performed on all fabrics at low (340 m s−1) and high velocity (620 m s−1). Observations and measurements were performed to determine failure mechanisms, energy absorption, transverse wave propagation, and system effects of multi-ply systems. Hybrid systems showed significant differences in specific energy absorbed (SEA), dependent on the layer order. The para-aramid hybrid systems impacted at 340 m·s−1 showed a significantly greater SEA when the fabrics were ordered with an increasing rather than a decreasing cover factor. At 620 m·s−1 the difference in SEA was less pronounced or absent entirely. It was concluded that hybridization would enhance the performance of a soft armor system and was likely to be most effective for the rear layers of the system where fabrics with a progressively increasing cover factor that were manufactured of fine (550 dTex) para-aramid yarns would offer an advantage. The front layers of the system, subjected to higher strain loading, would benefit from low cover factor fabrics (0.76), which maximize the dissipation of strain from the point of impact.