Crack Paths 2012

C12=C21=C13=C31=C23=C32=74.1 GPa, C33=178 GPa, C44=C55=105 GPa, C66=78.4 GPa.

All other elastic constants are 0.

The C Z Eare modeled using a formulation developed by Lorentz [20] and a C Z M

from Mi [21] with an initial perfect adhesion. The jump in the displacement field at

the cohesive interface is then linearly linked to the stress until it reaches a critical value

N. Meanwhile, a scalar damage parameter takes into account the irreversibility of the

damage process : =maxtime(/N). It is presented in Figure 2(a) and the parameters

Nmax = 800 M P aand

N = 24 m are taken from previous numerical studies. These

parameters are not the exact ones, but are sufficient to describe the competition between

the intragranular and intergranular crack propagation mechanisms [13]. The use of this

C Z Efomulation imposes a quadratic interpolation on the whole mesh.

a) C Z Mused for intergranular

b) Exampleof a refined zone

of the mesh

crack propagation

c) Schemeof the remeshing process

Figure 2. C Z Mused, an adaptive meshexample and a scheme of the remeshing process.

Remeshing Process

A remeshing process is used in order to refine the mesh around the crack tip and to

add new C Z E during the FE simulations. In this model, since all the grain boundaries

are considered as potential crack paths the remeshing procedure can only add C Z E

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