Damage Investigation on the Carbon Tows during Rewinding and Braiding Processes

During the manufacturing process, the fibrous materials used in composite reinforcements are subjected to many sources of damage that must be managed if the best possible quality is to be reached for the final product. More specifically, carbon fibers are subjected, during reinforcement manufacturing, to friction with mechanical components and with other tows and to excessive tensile loads due to specific configurations required by textile devices, which results in degradation that affects their mechanical properties and those of final products. While many studies have focused on carbon tow damage during the weaving process, roving quality control during the post-braiding steps, such as the rewinding or braiding processes, is less studied in the literature. In this study, an experimental approach was developed to quantify the damage inflicted on 12 K carbon tows during the rewinding and braiding processes using image analysis software. Based on these images, a damage criterion is defined to quantify the influence of the parameters associated with rewinding and braiding processes on degradation of carbon tows. During the rewinding stage, the influence of the process parameters on the degradation by friction of the tows was significant, but the properties (linear density and tenacity) of these carbon tows were little-modified. On the other hand, the great influence of the tension applied on tows on the inflicted damage was experimentally demonstrated, during both the rewinding and braiding steps, which may have resulted in a loss of tenacity of up to 27%.