Finite element modeling of mode I delamination growth in laminated DCB specimens with R-curve effects

This paper proposes a three-linear cohesive zone model (CZM) to capture the mode I delamination initiation and propagation behavior of unidirectional DCB specimens under large-scale fiber bridging conditions (R-curve behavior). This CZM is produced by superposing two bilinear CZMs and the required parameters are obtained from the experimental R-curve of a DCB specimen only knowing the initiation fracture toughness (Gi), the fiber bridging length (lFPZ) and the steady state toughness (Gss). The proposed method does not need the measurement of the crack tip opening displacement during the experiments and, therefore, it eliminates the current difficulties of the traditional CZMs in the simulation of delamination propagation under large-scale bridging.