A hybrid micromechanical-macroscopic model for the analysis of the tensile behavior of cavitating materials

Abstract

A new approach, which combines both micromechanical and macroscopic perspectives of deformation, was developed to simulate the uniaxial tensile deformation of cavitating materials. By this means, limitations and assumptions of previous models were avoided. These include the limitation to the analysis of a symmetric cavity array and a representative unit cell (microscopic models) and the assumption of a homogeneous cavity distribution and failure at a predefined critical cavity volume fraction (macroscopic models). The new model takes into account local variations in cavity density and the possible coalescence of discrete pairs of cavities not necessarily located on the same horizontal plane. The propensity for cavity coalescence via impingement or linkage (due to matrix rupture) was found to depend heavily on the initial cavity density. Simulations of the uniaxial tension test demonstrated that flow localization and thus failure occur earlier during the deformation and cavitation process when local cavity density variations are taken into account. However, the predicted cavity volume fraction at failure is the same for both the hybrid micro-macro and macroscopic models when the initial cavity density is high. In such cases, the predicted tensile ductility is therefore essentially identical.