A simplified use of Gp 2D approach

1 December 2013

by R. Bargellini, EDF R&D / AMA

The Gp approach of fracture mechanics enables the prediction of the initiation of a cleavage default. This deterministic approach is valid for an elastoplastic framework, even when unloading occurs. It has been developed at EDF R&D for the past fifteen years and accounts for the effects of small defects and warm pre-stressing.

A barrier to the wide-spread use of this approach is the need for a particular mesh, where the fault is represented by a notch, in front of which particular zones, called shavings, are defined.

The new CALC_GP and RAFF_GP commands allow to overcome the definition of these shavings. The user can now provide any mesh, in which the defect is still represented by a notch (sufficiently refined).

Before the mechanical calculation, the mesh may be refined in the area of ​​interest (downstream of the notch tip) with the new RAFF_GP command. The figure below presents a mesh before and after the refinement.

Figure 1 : Refinement of the mesh in the area of ​​interest with RAFF_GP

The calculation of the Gp parameter is done in post-processing of the mechanical computation through the CALC_GP command, which accepts any 2D mesh (3D meshes must still contain the predefined shavings). The zones are then reconstructed by groups of Gauss points, as shown in figure 2.

Figure 2: Reconstitution of the shavings zones with the CALC_GP command

Available in 11.3.7 and later versions for CALC_GP and in 12.0.15 and later versions for RAFF_GP.