The rupture mechanism assumes the presence of an initial defect, a place of stress concentration, after which the notch (case of our study) will be able to start.

It is therefore necessary to understand the mechanism of rupture and to delimit its volume of elaboration. This communication aims at locating and studying the critical size of this process zone, taking into account the loading conditions by examining them on steel specimens subjected to I + II mode in a volumetric approach.

This study aims to study the following axes:

1- Define the zone of elaboration of rupture by proposing new numerical methods.

2-Compare the extent of the plastic zone to the elaboration volume of the rupture.

To do this, two methods are developed: Stress gradient, plasticity criterion.

Keywords: Volumetric approach, notch, effective distance, stress gradient, mixed mode, plasticity criterion, plastic zone.