3. The mesh

For a mechanical calculation with local damage, linear or quadratic meshes can be used indifferently. On the other hand, it is advisable to have fairly homogeneous mesh sizes so that the dissipation is also homogeneous (reminder: local dissipation is linked to the size of the mesh). It is also advisable to have identified post-peak parameters on tests using approximately the same mesh sizes.

Most non-local models rely on quadratic meshes. The following table summarizes the elements available for each model.

	2D	AXI	3D
GRAD_VARI	TRIA6 QUAD8	TRIA6 QUAD8	TETRA10 HEXA20 PENTA15 PYRAM13
2DG	TRIA7 QUAD9
DIL	TRIA7 QUAD9 TRIA6 QUAD8		[*] _
INCO_UPG	TRIA6 QUAD8	TRIA6 QUAD8	TETRA10 HEXA20

Table 2: available meshes depending on the models

With regard to the fineness of the mesh, it should be noted that for the regularization of the problem to be effective, at least three meshes or even ten meshes (for modeling GRAD_VARI) are required for a damage band. Thus, if the size of the damaged zone is \(1\mathit{cm}\), in this zone, the mesh size must be less than \(3\mathit{mm}\) or even \(1\mathit{mm}\) for GRAD_VARI.

[1]

The 3D version will be available in version 10