Size effect for samples with blunt and sharp notches using linear cohesive crack law

The object of this work is to provide a more general formulation of the cohesive size effect curve to include structural configurations with blunt and sharp notches. An extensive campaign of accurate numerical simulations, based on the cohesive crack model, is performed to compute the Generalized Cohesive Size Effect Curves (GCSEC) for typical test configurations featuring both sharp and blunt notches. The results are analyzed with reference to the classical Baˇzant’s Size Effect Law (SEL) to investigate the relationship between GCSEC and SEL. This analysis shows that as specimen size tends to infinity, the SEL represents the asymptote of the GCSEC in the case of sharp notches, and that the SEL parameter known as the effective fracture process zone length is a material property, which can be expressed as a function of the Cohesive Crack Law (CCL) parameters. For blunt notches, however, the nominal strength of infinite size samples tends to a horizontal asymptote corresponding to the elastic limit. It is shown that the two results are not in contradiction because the effective fracture process zone length tends to zero as the radius of curvature tends to zero.