Fracture toughness evaluation for multidirectional CFRP by the Raman coating method

The Mode I fracture toughness for multidirectional carbon-fiber-reinforced plastics (CFRP) was investigated by using double-cantilever beam (DCB) specimens with Raman spectroscopy. A thin PbO film was deposited on the specimen surface by physical vapor deposition (PVD) as the pretreatment for strain measurement, and then the fracture toughness was determined from the results of Raman spectroscopy measurement. These results agreed with the results by conventional experimental methods and numerical analyses. The fracture surfaces of DCB specimens were observed by scanning electron microscope (SEM); the fracture surfaces differed because of different critical energy release rates.