Bending properties of non-crimp stitched carbon fabric reinforced composites of different knit patterns

Three kinds of non-crimp fabrics (NCF) of carbon fiber studied. The internal structures of each kind of fabrics is described together with bending tests to investigate the impact of knit pattern on mechanical properties of NCF composites. Biaxial fabric [45°/-45°] with chain stitch has better binding effect and smaller width of deformation induced by stitching yarns than biaxial fabric [0°/90°] with tricot stitch. Biaxial fabric [45°/-45°] reinforced composites have relatively less resin-rich areas and voids, the bending strength and modulus are higher than that of the biaxial fabric [0°/90°] reinforced composites. In contrast to biaxial warp knitted fabrics, unidirectional NCF reinforced composites have more accurate fibre orientation and less distortions or damages caused by the stitching yarns, thus higher bending strength and modulus.