POST-IMPACT MECHANICAL CHARACTERIZATION OF HMPE YARNS

The present work evaluates the mechanical behaviour of High Modulus Polyethylene (HMPE) yarns after being impacted by sudden axial loads. The influence of loading conditions on the structural integrity of yarns is assessed by tensile, fatigue, and creep tests before and after the impact events. The impact loads were inferred by drop-weight adopting a 300 mm height and weights corresponding to 4, 5, and 6 % of Yarn Breaking Load (YBL). At 5 % YBL, most specimens fail after the impact, and at 6 % YBL, all specimens fail. The application of 4 % YBL tests results in enhanced creep and fatigue resistances and a decrease in the tensile resistance. Finally, a Scanning Electron Microscopy (SEM) analysis showed that the yarn filaments tend to straighten after the impact, while a decrease in their diameter is noticed due to the longitudinal deformation.