Fracture behavior of hybrid composites containing both short and continuous fibers

Abstract A method for improving the fracture resistance of brittle polymer composites was explored. This method involved the incorporation of short fibers in a thermosetting resin before being used for impregnating the continuous fibers or fabrics. The impact fracture energy and the maximum load experienced by the hybrid can be associated with the parameters of short fibers (e.g., volume fraction and mechanical properties). Electron micrographs of the fracture surfaces of the specimen loaded under mode I and mode II conditions indicate that the short fiber modified composites have a significantly greater fracture surface area and higher level of plastic deformation than the unmodified composites. The data from all the tests demonstrate that adding a small amount of short fibers can significantly improve the interlaminar fracture toughness and impact resistance of graphite/epoxy composites. However, a high volume fraction of added short fibers could make it difficult to out‐gas during compression‐molding, leading to a high void content and reduced mechanical properties of composites.