Carbon/Epoxy Composites Fabricated by Vacuum Consolidation of the Interleaved Layup of Prepregs and Dry Fibers

Abstract

The out-of-autoclave (OOA) or vacuum bag only (VBO) process uses partially impregnated prepregs for composite laminates, where gases and volatiles are removed by vacuum through the dry region of the prepregs during the consolidation. In this study, the fully impregnated carbon fiber prepregs and dry carbon fiber were laid up in an interleaved manner to form a hybrid laminate similar to the laminate with partially impregnated prepregs. By using the volumes of the fiber pore and resin in the hybrid laminate, we defined the saturation degree of a hybrid laminate. Three types of hybrid laminates were fabricated and they had different saturation conditions: over-saturation, saturation, and under-saturation. Tensile test was performed to find out how the saturation index affected the tensile properties of the composites. Also, the dual beam focus ion beam system (FIB) was used to observe the cross-section of the hybrid laminate. The result shows that if the saturation index is greater than one, the hybrid laminate will have competitive tensile properties as the composite manufactured by the conventional autoclave process.