A general framework to derive nonlinear elastic and elastoplastic macroscopic material models from granular micromechanics is proposed. Like the classical pseudo-grain contact-based homogenization methods of hyperelasticity, originated in the 1980s, reference solutions for closed-form hyperelastic material models are analytically derived from the microscale inter-granular contact mechanics. However, unlike prior methods, the proposed homogenization framework defines an incremental variational principle that renders the traditional solutions extensible to plastic solids, i.e., closed-form hyperelastoplastic material models. The proposed framework is used to develop a novel granular micromechanics-based macroscopic model for pressure-sensitive plasticity with grain-contact decohesion, which expresses a deviatorically- and volumetrically-coupled nonlinearly elastic response. This class of material models is formulated mathematically by aggregating the mesoscale mechanical response due to microscale failure events like debonding of and slip between representative pseudo-grains, such that macroscopic inelastic parameters are explicitly related to their microscale counterparts, e.g., the friction coefficient governing inter-granular slip. Numerical examples and comparison to measurements from the literature, including pure concretes under triaxial compaction, are provided to investigate model predictions and demonstrate calibration to experimental data.
2022-04-06 08:00:00
