Super-Arrhenius dynamics for sub-critical crack growth in two-dimensional disordered brittle media

Abstract : Taking into account stress fluctuations due to thermal noise, we study thermally activated irreversible crack growth in disordered media. The influence of material disorder on sub-critical growth of a single crack in two-dimensional brittle elastic material is described through the introduction of a gaussian rupture threshold distribution. We derive analytical predictions for crack growth velocity and material lifetime in agreement with direct numerical calculations. It is claimed that crack growth process is inhibited by disorder: velocity decreases and lifetime increases with disorder. More precisely, lifetime is shown to follow a super-Arrhenius law, with an effective temperature $\theta-\theta_d$, where $\theta$ is related to the thermodynamical temperature and $\theta_d$ to the disorder variance.