Investigation on the knittability of glass yarn

Knitted fabric reinforcements gain interest in the composite industry for their excellent drapability, impact resistance and net-shape manufacturability. However, little attention has been given to the fabrication damages on high-performance yarns during the knitting process, which were proved to be of strong influence on the final composite performance. In this paper, investigations were carried out on the knittability of glass yarn. By simplifying the knitting process into separate yarn-needle hook systems, designed experiments were carried out to evaluate the yarn-breaking process under tensile, bending and abrasive actions. Acoustic emission (AE) technology was used during the above tests to represent the fiber-breakage history. Together with the SEM photos and theoretical analysis, the reasons for glass filament breakage at low yarn tension were found to be the compound results of the bending stress and shear stress generated by contact stress concentration.