This paper presents a novel experimental method for impacting microscale single fibers under dynamic multiaxial loading conditions. Experimental setup is developed by modifying a 0.25-inch diameter Hopkinson bar to directly impact fibers. Using this setup, ultrahigh molecular weight polyethylene (UHMWPE) Dyneema® SK76 single fibers, with average diameter 17 µm, are transversely impacted with indenter radii of 200 (blunt), 20 (sharp), and 2 (razor) µm at velocities of 10 and 20 m/s, corresponding to nominal strain rates of 4000–6300 s⁻¹. Compared to high strain rate (1156 s⁻¹) uniaxial tensile loading, significant reductions in failure strains are measured for transverse impact with blunt (34%), sharp (39%) and razor (61%) indenters. The reduction in tensile properties is attributed to strain rate and multiaxial stress-states induced by impactor geometries; while all three geometries induced transverse compression, sharp and razor induced a greater degree of transverse shear, observed by failure surfaces.

本文提出了一种在动态多轴载荷条件下冲击微米级单纤维的新型实验方法。通过修改直径0.25英寸的霍普金森棒以直接冲击纤维来开发实验装置。使用此设置，平均直径为17 µm的超高分子量聚乙烯（UHMWPE）Dyneema®SK76单纤维以10的速度分别以200（钝），20（锐）和2（剃刀）的压头半径横向受到冲击。和20 m / s，对应于4000–6300 s ^-1的名义应变率。与高应变率（1156 s ^-1）单轴拉伸载荷，用钝头（34％），锋利（39％）和剃刀（61％）压头测量横向冲击时，破坏应变显着降低。拉伸性能的下降归因于由冲击器几何形状引起的应变率和多轴应力状态。而这三个几何形状均引起横向压缩，而锐利和剃刀则引起较大的横向剪切，这是通过破坏面观察到的。