Evaluation of Dynamic Fracture Toughness of Unidirectional CFRP Laminates

In the present paper, dynamic inter-laminar fracture toughness are estimated for carbon fiber reinforced plastics (CFRP). In the experiments, split Hopkinson's bar test was applied to dynamic end notched flexure (ENF) test. The dynamic deformation of the specimen is approximated by beam theory with Laplace transform. The mode II fracture toughness of unidirectional CFRP was estimated by the analyzed deflection of the specimen employing the scheme of J-integral with the measured impulsive load and reactions at the supported points. Through some numerical calculations, validity of the J-integral for the dynamic ENF test is confirmed. In addition, as a experimental result, dynamic inter-laminar fracture toughness of CF/EPOXY unidirectional specimens are estimated and it indicates dependency on deflection rate.