  The modeling of crack propagation in a heterogeneous material using a phase
field model is studied numerically in a simple test case: the crack meets a
wedge of higher fracture energy. It is shown that when the crack cannot enter
the wedge, phase field results are in qualitative agreement with theoretical
predictions with moderate quantitative discrepancies. When the crack can
propagate in both regions, numerical results show that the interplay of diffuse
interface modelling used in the phase field model with the interface between
the two regions induces spurious effects that are unphysical.
