Effect of hybrid ratio on mechanical properties of carbon/aramid hybrid fiber multi-layered biaxial weft knitted fabric reinforced composites

Carbon/aramid fiber hybrid multi-layered biaxial weft knitted fabric was prepared in term of intraply hybridization. The mechanical properties and effect of hybrid ratio on mechanical properties were studied. Through uniaxial tension and three-point bending experiments, the tensile and bending properties and effect of hybrid ratio on mechanical properties were obtained. The results show that the tensile properties of composites are improved by adding aramid fibers according to a certain hybrid ratio, which shows a positive hybrid effect. Due to the addition of aramid fibers with good elongation, the tensile fracture elongation of the composites obviously increases, and the failure modes of the composites appear complete brittle fracture mode (C12 material failure mode) and "broom" fiber fracture mode (C8A4, C6A6 material failure mode). Besides, the fracture toughness of carbon fiber reinforced composites is effectively improved by adding aramid fibers at a certain hybrid ratio. The flexural strength and modulus of carbon/aramid hybrid MBWK fabric reinforced composites decrease with the increasing of hybrid ratio. With aramid content changing from 42% (volume fraction, the same below) (C6A6) to 59. 2% (C4A8), the decreasing ratio of the bending strength and bending modulus are high. The bending deflection of 0 degrees samples with a hybrid ratio of 59. 2% (C4A8) is the highest, the value is 7. 49 mm, which is much higher than that of pure aramid fiber or carbon fiber reinforced composites. The bending deflection of all 90 degrees samples is higher than that of pure aramid fiber or pure carbon fiber reinforced composites, which shows the positive hybrid effects.