Influence of the Manufacturing Process on the Tensile Stress-Strain Response of Hybrid Glass/Carbon and Carbon/Carbon Composites

Despite the numerous advantages of fibre reinforced polymers (FRP) composites, ductility is still a major problem of these materials. Usual FRP composites are stiff and strong with little or no warning before final failure. The mentioned drawback can be mitigated using unidirectional (UD) hybrid composites (i.e. composites in which two or more different reinforcing materials are combined in the same polymeric matrix). In these materials the development of tensile pseudo-ductile behaviour during the failure process can be achieved. The amount of resin used to manufacture hybrid FRP composites is responsible for significant changes at their tensile stress-strain curve. It is believed that these changes are dependent on the interlaminar fracture toughness of the interface between layers. In the present work, the effect manufacturing methods on the tensile properties of hybrid composites was studied. Hand lay-up and vacuum bagging techniques were compared. Three combinations of dry unidirectional fabric materials were used to produce hybrid FRP composites, namely: i) high-modulus carbon, ii) standard carbon, and iii) E-glass. An epoxy-based resin was used as matrix. Failure modes, tensile elastic modulus, strength, and stress-strain curve were analysed. Finally, experimental results were analytically simulated.