Approximate analysis of necklace coalescence

Abstract

Two recent models of void coalescence in columns are revisited to provide simpler, approximate expressions for the effective yield surface. Unlike the exact criteria, these are not upper-bound preserving but provide more flexibility in numerical implementation of the models. Both models correspond to limit analysis on the same geometry, namely a cylindrical void of finite height embedded in a cylindrical cell. One model employs a continuous velocity field, the other a discontinuous, yet kinematically admissible velocity field. The approximations are assessed by direct comparison to the exact criteria for several sets of the internal parameters.