On cavitation instabilities with interacting voids

When a single void grows in an elastic–plastic material a cavitation instability may occur, if the stress triaxiality is sufficiently high. The effect of neighbouring voids on such unstable cavity growth is studied here by comparing two different models. The first model considers a periodic array of voids, which allows for different rates of growth of two different types of voids. The second model considers a single discretely represented void embedded in a porous ductile material. It is shown that these two models represent very different interaction behaviour. According to the first model small voids so far apart that the radius of the plastic zone around each void is less than 1% of the current spacing between the voids, can still affect each others at the occurrence of a cavitation instability such that one void stops growing while the other grows in an unstable manner. On the other hand, the second model only accounts for effects of neighbouring voids that are inside the plastic zone surrounding the central void. The unit cell models analysed are axisymmetric, considering the full range of unstable stress states with the transverse true stress either larger than or smaller than the axial true stress.