An incremental finite element model is presented that predicts the growth of a crack through a 2D
structure containing round pores. The crack is deflected due to the influence of the pores on the strain field
and might grow into a pore. Furthermore, the initiation of cracks from the pore surfaces is modelled with a
combined stress-energy criterion. The model contributes to the understanding of toughening mechanisms in
heterogeneous materials. It is capable of showing the influence of the pore content, the pore arrangement and
pore shape on the resistance to crack propagation.