Subcritical statistics in rupture of fibrous materials: Experiments and model

We study experimentally the slow growth of a single crack in a fibrous material and observe stepwise growth dynamics. We model the material as a lattice where the crack is pinned by elastic traps and grows due to thermally activated stress fluctuations. In agreement with experimental data we find that the distribution of step sizes follows sub-critical point statistics with a power law (exponent 3/2) and a stress-dependent exponential cut-off diverging at the critical rupture threshold.