A Multiscale Analysis of Void Coalescence in Nickel

An internal state variable void coalescence equation developed by Horstemeyer, Lathrop, Gokhale, and Dighe (2000, Theor. Appl. Fract. Mech., 33(1), pp. 31–47) that comprises void impingement and void sheet mechanisms is updated based on three-dimensional micromechanical simulations and novel experiments. This macroscale coalescence equation, developed originally from two-dimensional finite element simulations, was formulated to enhance void growth. In this study, three-dimensional micromechanical finite element simulations were employed using cylindrical and spherical void geometries in nickel that were validated by experiments. The number of voids, void orientation, and void spacing were all varied and tested and simulated under uniaxial loading conditions. The micromechanical results showed excellent agreement with experiments in terms of void volume fractions versus strain and local void geometry images. Perhaps more importantly, the macroscale internal state variable void coalescence equation did not require a functional form change but just a coefficient value modification.