Experimental results of mode I interlaminar fracture toughness of graphite/PEEK composite are presented. A fracture mechanics approach is used for the evaluation of double-cantilever beam tests. The effect of specimen thickness on the toughness was investigated. It is found that for the interlaminar fracture of graphite/PEEK composite the value of the interlaminar fracture energy generally increases as the specimen thickness increases. Fracture surface was examined using scanning electron microscope.
