Evaluation of dynamic fracture toughness of unidirectional CFRP laminates

In the present paper, dynamic interlaminar fracture toughness of carbon fib er reinforced plastics (CFRP) is estimated by split Hopkinson's pressure ba r test using end notched flexure (ENF) specimens. The dynamic deformation o f the specimen is approximated by classical beam theory with Laplace transf orm. The Mode II fracture toughness of unidirectional CFRP is computed by t he analyzed deflection of the specimen employing the scheme of J -integral with the measured impulsive load and reactions at the supported points. Thr ough some numerical calculations, the validity of the J -integral for the d ynamic ENF test is confirmed. The experimental results for carbon/epoxy lam inates show that dynamic interlaminar fracture toughness of the unidirectio nal specimen has dependency on a deflection rate.