Nucleation, Creep, and Dynamic Tensile Fracture Are Described by Extended LEFM.

We experimentally validate a new description of brittle tensile fracture that extends linear elastic fracture mechanics (LEFM) to account for the 2D geometry of propagating cracks in plates of finite thickness, W. We show that cracks nucleate below the Griffith length at a critical stress threshold. They then creep (at constant velocities orders of magnitude below the Rayleigh wave speed) until expanding to W. Only then do cracks undergo dynamic 1D fracture. The new theory quantitatively describes all of these dynamics. These results have important ramifications to all aspects of material failure.