Investigation of co-cured liquid composite molding and interlaminar property for carbon fiber composites

The carbon fiber/epoxy resin matrix composite laminates were fabricated using co-cured liquid composite molding (LCM). The compaction of laminates and diffusion of the two kinds of resins were investigated. Mode-I delamination fracture toughness and short beam shear strength were measured to evaluate the interlaminar property of the co-cured laminates and were compared with those of laminates processed by prepreg molding and liquid composite molding. Moreover, the effects of fiber orientation at the interface between prepreg part and LCM part on G_IC were studied. The results show that the laminates processed by co-cured LCM have high compacting degree in the intralaminar plies and have no obvious resin-rich area between plies. The two kinds of resins at the interface between prepreg part and LCM part diffuse to some extent. Affected by the diffusion of the two kinds of resins at the interface, the interlaminar fracture toughness of co-cured laminate is equivalent to the average of those of the prepreg laminate and LCM laminate, while short beam shear strength is determined by the weaker part. The fiber orientation at the interface between prepreg part and LCM part has significantly influence on G_IC, and [45/90] fiber orientation has a better resistance to interlaminar fracture and propagation of delamination.