A new article with E. Tanné, T. Li, J.-J. Marigo and C. Maurini tackles the issue of crack nucleation in variational phase-field models of fracture is to appear in the Journal of Mechanics and Physics of Solids.
We show that carefuylly designed models can reconcile strength and toughness criteria and account for size effects. We compare numerical simulations and experiments in a wide range of brittle materials and geometries including U- and V-notches.
Generalized critical stress intensity factor in a U-notch as a function of the non-dimensional notch radius. Numerical simulations vs. experiments compiled in (F. J. Gómez, G. V. Guinea, and M. Elices, 2006, Int. J. Fracture DOI:10.1007/s10704-006-0066-7)