Effect of void locking by inclusions upon the plastic behavior of porous ductile solids—part II: theoretical modeling and numerical study of void coalescence

The aim of this work is to pursue the modeling of the influence of inclusions upon the behavior of porous ductile materials, initiated in Part I devoted to void growth prior to coalescence, by now considering coalescence of voids. Using the void growth model developed in Part I accounting for both void shape effects and effect of inclusions, an approximate, analytical model for coalescence incorporating the effect of inclusions is derived. Its principle consists in accounting for the strain-induced anisotropy of the void distribution by schematizing the RVE considered as made up of 3 superposed horizontal layers, 2 sound ones surrounding a highly porous one. The mechanical fields are considered as homogeneous in each zone, the behavior of the porous one being described using the model of Part I. The treatment distinguishes between the pre-coalescence phase during which the RVE is entirely plastic, and the coalescence phase which involves concentration of the plastic strain within the sole central porous layer. The model predictions are compared to numerical results from FE simulations and the agreement is generally found to be good.