ON THE GRIFFITH CRITERIA FOR BRITTLE-FRACTURE IN COMPRESSION

Pre-existing flaws in materials are the potential source for brittle f racture in compression just as in tension. As in tension, both the str ess and energy criteria should be taken into account for brittle fract ure in compression. In the model presented, flaws are represented by t hree-dimensional ellipsoids, thus removing certain limitations of prev ious two-dimensional models. The formulation of the changes in the pot ential energy of the applied load and the strain energy of the infinit e medium due to the introduction of an ellipsoidal void is presented a nd the implementation of the numerical calculation of the stress conce ntration and the energy release rate is developed. The required three- dimensional theory for a better understanding of brittle fracture in c ompression is provided.