Evaluation of Dynamic Fracture Toughness of Unidirectional CFRP Laminates

Abstract

In the present paper, dynamic interlaminar fracture toughness of carbon fiber reinforced plastics (CFRP) is estimated by split Hopkinson's pressure bar test using end notched flexure (ENF) specimens. The dynamic deformation of the specimen is approximated by classical beam theory with Laplace transform. The Mode II fracture toughness of unidirectional CFRP is computed 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, the validity of the J-integral for the dynamic ENF test is confirmed. The experimental results for carbon/epoxy laminates show that dynamic interlaminar fracture toughness of the unidirectional specimen has dependency on a deflection rate.