Fatigue behavior characteristics of hybrid composites with nonwoven carbon tissue

Fatigue behavior characteristics of hybrid composites with nonwoven carbon tissue (NWCT) are investigated under tension-tension cyclic loadings. The hybrid composites were made by stacking NWCT-prepreg and CFRP-prepreg. To investigate the fatigue effects of the NWCT stacking, ten kinds of laminates were studied; i.e., NWCT composites, CFRP transverse [90]₁₂, off-axis [45]₁₂ and angle-ply [±45]_3S, hybrid transverse ([90//90//90//90//90//90/]_S, [//90//90//90//90//90/]_S), off-axis ([45//45//45//45//45//45/]_S, [//45//45//45//45//45//45/]_S) and angle-ply ([+45// -45//+45//-45//+45//-45]_S, [//+45//-45//+45//-45//+45//-45]_S). The symbol "//" means that the NWCT-prepreg is located between the CFRP layers. The effects of NWCT -on the tension-tension fatigue life, the residual strength and stiffness of angle-ply hybrid specimens were evaluated after fatigue tests. The fatigue behaviors of the hybrid composites were dependent on that of the NWCT composites. The fracture surfaces of the hybrid specimens and the fracture process on the side-edge section were observed with an optical microscope, and the failure mechanism was analyzed.