Slow crack propagation through a disordered medium: Critical transition   and dissipation
  We show that the intermittent and self-similar fluctuations displayed by a slow crack during the propagation in a heterogeneous medium can be quantitatively described by an extension of a classical statistical model for fracture. The model yields the correct dynamical and morphological scaling, and allows to demonstrate that the scale invariance originates from the presence of a non-equilibrium, reversible, critical transition which in the presence of dissipation gives rise to self organized critical behaviour. 
G. Pontuale, F. Colaiori and A. Petri
cond-mat.dis-nn cond-mat.stat-mech