Validation of mode Ⅱ cohesive law obtained using the direct method with short-fiber-reinforced thermoplastic adhesively bonded end-notched flexure joints

Abstract

In this study, we utilized end-notched flexure (ENF) specimens constructed from short-glass-fiber-reinforced plastic bonded with epoxy adhesive to conduct ENF tests aimed at estimating cohesive zone model (CZM) parameters under mode II loading using a direct method. Two distinct types of J-integral values were evaluated during the analysis. The first treated the joint as an elastic body, corresponding to the energy release rate. The second accounted for the plastic deformation of the joint. Subsequently, we derived two sets of traction-separation laws (TSLs) by differentiating the two types of J-integral values with respect to the shear displacement of the crack tip. Finally, we performed finite element analysis on the ENF specimens using the two sets of CZM parameters obtained from the two identified TSLs. The resulting load–displacement curves were compared with experimentally acquired curves. The comparison revealed that the curve estimated using the CZM parameters based on the energy release rates was closely aligned more with the experimental curve than with that based on the J-integral values.