Identification of parameters of a bi-linear cohesive-zone model using analytical solutions for mode-I delamination

A novel parameter identification method for a bi-linear cohesive-zone model (CZM), based on closed-form analytical solutions for mode-I delamination in a double cantilever beam (DCB), is proposed. The parameters to be identified are the area under the traction-separation law of the CZM, the maximum traction and the initial (linear-elastic) stiffness. Using the three-phase analytical solution, each parameter is identified separately from a different phase. The proposed method requires only the measurement of the load-point displacement and the applied load, while the measurement of the crack length is not necessary. Compared to methods that use complex numerical models and sophisticated optimisation algorithms, the proposed method is extremely fast and robust. Using experimental data from the literature, parameter identification results are presented. It is shown that the bi-linear CZM with identified parameters can be used to model delamination in a DCB for many different combinations of bulk material and adhesive with an acceptable level of accuracy, except for the case of delamination of composites with fibre bridging.