AbstractIn the present work, constraint effects on growth curves of a mode-I crack are determined using a triaxiality dependent cohesive model. Plane strain elastic-plastic analysis based on the modified boundary layer formulation is performed and for modeling the fracture process, the cohesive parameters and the mechanical properties for a mild steel are taken from literature. From the analysis, the resistance curves for a range of constraint parameter are obtained. A discussion is developed on the effectiveness of the triaxiality dependent model in capturing the well-known effect of constraint and also on the effect of the two model parameters on the resistance curves.