Energy released for branching and kinking cracks

Energy released due to the appearance of a very small branch at the tip of a main crack is calculated. Method for determining the G(alfa) factor is based on integrating the product of the known stress components released along the plane of the small branch and corresponding displacements obtained using numerical FEM approach. This procedure makes it possible to calculate both GI( alfa) and GII(alfa ) energy components. Results are compared with a different approach obtained directly by considering local values of the stress intensity factors KI(alfa) and KII(alfa), valid for the branch tip. Some additional effects of a sharp notch appearing just behind the branch crack are also described.