In Situ Visual Observation of Fracture Processes in Several High-Performance Fibers

Abstract

Three different high-performance fibers have been imaged in situ during Kolsky bar tensile loading using two different techniques, namely optical microscopy and phase contrast imaging (PCI). Kevlar® KM2, Dyneema® SK76, and S-2 Glass® fibers have been pulled using an instrumented Kolsky bar, thereby shedding light on the failure process of each fiber type. Both the Kevlar® KM2 fiber and Dyneema® SK76 fiber exhibit rupture defined by varying degrees of fibrillation, with the former typically showing longer fibrillated ends than the latter. S-2 Glass® failure was found to exhibit a brittle fracture mode at a single point, although post-mortem analysis commonly yielded disintegration of the fiber gauge length, which is concluded to occur post the initial break due to fiber snap back or bending. Finally the efficacy of utilizing the PCI technique to achieve higher levels of spatial and temporal resolution is discussed.