The goal of this study is to simulate crack growth in miniC(T) fracture tests using a Cohesive Zone Model (CZM) in order to derive the evolution of the toughness in the Ductile-to-Brittle Transition (DBT) region. The calibration method used is adapted from [1] and only requires low-temperature experiments. For a given temperature, it is assumed that the cohesive energy increases with the fracture probability, and that the shape of the CZM traction-separation law varies from a triangle to a trapezoid when the cohesive energy is greater than a value identified using elasto-plastic simulations. The cohesive parameters are determined using two calibration procedures. The first is performed using two experimental load-displacement curves. The second involves finding the cohesive energy leading to the right fracture toughness value given by the master curve for three different temperatures and two fracture probabilities. An exponential evolution of the cohesive energy with temperature is proposed. Cohesive energy is also assumed to depend on fracture probability.
Simulations of mini-C(T) toughness tests are then performed for cumulative failure probabilities of 2%, 50% and 98% at different temperatures. A good agreement is observed between the toughness computed from the simulations and the master curve approach.