A continuum mechanics approach to some problems in subcritical crack propagation

The results of the so-called energetic approach to fracture for the cases of a sharp crack without and with a cohesive zone are briefly reviewed with particular attention to the crack tip singularity analysis and to the issue of energy dissipation due to crack propagation. The case of a crack with a cohesive zone removing all thermomechanical singularities is then further analyzed, focusing the attention on the question of the thermodynamic admissibility of subcritical crack growth, and on some of the hypotheses that lead to the derivation of subcritical crack growth laws. A two-phase cohesive zone model for discontinuous crack growth is presented and its thermodynamics analyzed, followed by an example of its possible application.