Effect of twist on transverse impact response of ballistic fiber yarns

• Characterization of transverse impact response of twisted fiber yarns.
• Determination of the twist effect on transverse impact response of fiber yarns.
• Providing optional design of soft body armor fabrics for better ballistic performance.

A Hopkinson bar was employed to conduct transverse impact testing of twisted Kevlar KM2 fiber yarns at the same impact speed. The speed of Euler transverse wave generated by the impact was measured utilizing a high speed digital camera. The study included fiber yarns twisted by different amounts. The Euler transverse wave speed was observed to increase with increasing amount of twist of the fiber yarn, within the range of this investigation. The higher transverse wave speeds in the more twisted fiber yarns indicate better ballistic performance in soft body armors for personal protection.