Effect of Manufacturing Parameters on the Tensile Properties and Yarn Damage of Glass Fiber Warp-knitted Net Preforms

Knitted fabric reinforcements gain interest in the composite industry for their excellent drapability, impact resistance, and net-shape manufacturability. Much research on the mechanical properties of knitted fabric reinforced thermoset and thermoplastic composites are available in the literature. However, to reduce the complexity in analysis and calculation, the loop architectures studied in these researches, either weft-knit or warp-knit, were very simple and lack of diversity. Additionally, limited attention has been given to the glass yarn damage during knitting, which have been proved to have a significant effect on the performance of the final composites. In this article, six-bar warp-knitted net preforms fabricated of glass plied yarns were studied. Eleven kinds of net preforms with different lapping movements, different take-up values, and different run-in ratios were fabricated and their mechanical performances as well as yarn damage during knitting were evaluated. The results showed that yarn damage and preform performance are highly related with the manufacture parameters from which optimum machine settings for each kind of preform could be delivered.