Relationship between cohesion, processability and bending behavior of carbon rovings

Many manufacturing processes of fibrous composites involve fiber movement to obtain a targeted fibrous preform before the resin is injected or polymerized. The ability of the fibers to move within the yarn can be named “cohesion.” To obtain a correct preform, it is of great importance to know and master yarn cohesion. As there is currently no available method to characterize yarn cohesion upstream, the process parameters have very often to be tuned using lengthy trial and error strategies. This paper proposes to address this issue, demonstrating that the yarn cantilever bending test is a very promising and efficient candidate to characterize and quantify yarn cohesion. In addition, the test can be easily performed in an industrial context and is sensitive enough to discriminate small variations in cohesion, even small discrepancies resulting from the yarn manufacturing process. Above all, thanks to real manufacturing tests on different yarns, this paper shows that the upstream identification of cohesion using the proposed cantilever bending test achieves the goal of predicting the yarn processability.