Micromechanics-based modelling of post-yield behavior of porous materials and its effect on hardness properties from conical indentation

Based on a multi-scale approach comprising a multi-scale material model, on the one hand, and a respective finite-element (FE) model, on the other hand, the indentation response of porous materials is examined. The considered material is assumed to consist of a homogeneous Drucker-Prager-type matrix-phase containing spherical pores, where the macroscopic strength criterion is obtained from nonlinear homogenization as proposed by Barthélémy and Dormieux. As regards modeling of the material behavior after onset of yielding, two types of behavior originating from different post-yield characteristics of the matrix material (ductile and quasi-brittle) are considered. The material model is implemented in a FE program within the framework of elastoplasticity and applied to the analysis of indentation experiments. The so-obtained relations provide first insight into the influence of the post-yield behavior of the matrix material on the hardness of porous materials.