On the multiaxial yielding and hardness to yield stress relation of nanoporous gold

We investigate the multiaxial behavior of nanoporous gold (np-Au) using finite element simulations on tomographic reconstructions, and its inferences of the hardness-to-yield strength ratio from nanoindentation and microcompression experiments on np-Au. Plane stress and axisymmetric loading simulations were carried out on real np-Au structures and simulated spinodal structures. The predicted initial yield response of spinodal and np-Au is nearly identical, while disagreeing with the Deshpande-Fleck foam yield criterion. A qualitative comparison of np-Au simulations with Deshpande-Fleck criterion suggests a plastic Poisson ratio of 0.23, corresponding to a hardness-to-yield stress ratio of 2.7 which is in remarkable agreement with experiments.