Characterization of the fracture toughness property (G1c) of composite laminates using the double cantilever beam specimen

The results of a study on the interlaminar fracture toughness properties (G_1c) of four unidirectional carbon fiber epoxy materials are presented. The selected materials included Narmco 5245C, Hexcel F584, and American Cyanamid 1806 resins reinforced with Hercules IM6 fibers and for a baseline material Narmco 5208 reinforced with T300 fibers. The G_1c values determined on Double Cantilever Beam specimens were found to range from 93 to 370 J/m². The higher values may partly result from fiber bridging during fracture. This paper discusses specimen configuration, test procedure, and the Scanning Electron Microscope results.