Effect of void cluster on ductile failure evolution

The behavior of a non-uniform void distribution in a ductile material is investigated by using a cell model analysis to study a material with a periodic pattern of void clusters. The special clusters considered consist of a number of uniformly spaced voids located along a plane perpendicular to the maximum principal tensile stress.

A plane strain approximation is used, where the voids are parallel cylindrical holes. Clusters with different numbers of voids are compared with the growth of a single void, such that the total initial volume of the voids, and thus also the void volume fractions, are the same for the clusters and the single void.

In the comparison it is essential that local void coalescence inside the clusters is accounted for, since this allows for considering the rate of growth of the single larger void that results from coalescence in the cluster. To obtain a parametric understanding, different transverse stresses on the unit cell are considered to see the influence of different levels of stress triaxiality.

Also considered are different initial ratios of the void spacing to the void radius inside the clusters. And results are shown for different levels of strain hardening in the material.