Nucleation from a cluster of inclusions, leading to void coalescense

A cell model analysis is used to study the nucleation and subsequent growth of voids from a non-uniform distribution of inclusions in a ductile material. Nucleation is modeled as either stress controlled or strain controlled. The special clusters considered consist of a number of uniformly spaced inclusions located along a plane perpendicular to the maximum principal tensile stress.

A plane strain approximation is used, where the inclusions are parallel cylinders perpendicular to the plane. Clusters with different numbers of inclusions are compared with the nucleation and growth from a single inclusion, such that the total initial volume of the inclusions is the same for the clusters and the single inclusion.

After nucleation, local void coalescence inside the clusters is accounted for, since this makes it possible to compare the rate of growth of the single larger void that results from coalescence in the different clusters. Nucleation parameters leading to rather early nucleation, or to later nucleation, are considered.

Also, different transverse stresses on the unit cell are considered to see the influence of different levels of stress triaxiality, and results are shown for different levels of strain hardening in the material.