The effect of the micro-structure of polypropylene fibers on plain-woven fabrics for flexible protection under low-velocity falling-ball impact

Fabrics with a higher level of inter-yarn friction usually demonstrate better impact resistance, as suggested by various studies on the impact response of ballistics-resistant fabrics. Over the past decade, significant efforts have been made to improve the frictional properties of fabrics, for example, with surface coatings. However, the influence of fiber micro-structure on the frictional coefficient of yarns has not been extensively studied. In this paper, a method is proposed for improving inter-yarn friction by using profiled fibers with non-circular cross-sections and twisted yarns. To explore whether fabrics made from these profiled fibers offer superior impact resistance to conventional circular-fiber fabrics, a fibrous surface friction test was conducted to measure the frictional coefficient of yarns composed of profiled fibers. Additionally, finite-element analysis and a falling-ball impact experiment were conducted to examine the protection performance and the energy dissipation mechanism of plain-woven fabrics composed of fibers with three different cross-sectional shapes under low-velocity impact. Based on the test results, it was deduced that fibers with such cross-sectional shapes as trilobal and cruciform shapes exhibit a slightly higher surface friction than their circular counterparts, thereby facilitating greater yarn engagement in energy absorption during low-velocity impact. This enhanced interaction leads to an improved impact resistance capacity.