Influence of yarn gaps on the mechanical performance of braided carbon fiber reinforced plastics

This study bases on the analysis of yarn gaps which typically occur during the production of braids due to deviation of process parameters. For mechanical analysis comparable yarn gaps were placed in samples made of defect-free braids. The yarn gap orientation in the samples was changed in several steps relative to the load direction. Samples were fabricated via VAP and RTM and tested in tension, compression and shear. Depending on the impregnation method and the yarn gap orientation the influences on mechanical performance differ. The results vary relative to the gap-free reference from slight differences till a reduction of 36% of the tensile strength. This drop is explained by a local increase of yarn undulation. © 2018 Carl Hanser Verlag, München.