6. The Cohesive Zone Model

According to what has been summarized in the previous chapters, simulations are performed with the Rousselier and the Gurson-Tvergaard-Needleman (GTN) models predicting the crack propagation of the C(T)-specimens with different initial crack positions, i.e., the initial crack located in the BM, in the centre of the FZ and at the interface between the FZ and the HAZ. As explained in the previous chapters, the phenomenological model—the cohesive model—is able to describe ductile and brittle fracture behaviour of materials when the proper traction-separation law is adopted. In this chapter, the dimensions and the mechanical properties of different weld regions are derived from the previous chapters. Compact tension specimens [C(T)25 with 20% side groove] are investigated with the cohesive model. The numerical simulation results are compared with the experimental one in terms of the F-COD- and J_R-curves.