Multiscale modeling and characterization of coupled damage-healing-plasticity for granular materials in concurrent computational homogenization approach

Abstract

A multiscale modeling and characterization method for coupled damage-healing-plasticity occurring in granular material is proposed. The characterization is performed on the basis of multiscale modeling of granular material in the frame of concurrent second-order computational homogenization method, in which granular material is modeled as gradient-enhanced Cosserat continuum at the macroscale. The damage-healing-plasticity is characterized in terms of meso-structural evolution of discrete particle assembly within representative volume elements (RVEs) assigned to selected local material points in macroscopic continuum, with no need to specify macroscopic phenomenological constitutive models, failure criteria along with evolution laws, and associated macroscopic material parameters.The proposed modeling and characterization method for coupled damage-healing-plasticity in granular material is comprised of the following three constituents. The incremental non-linear constitutive relation for the discrete particle assembly of RVE is first established. Then the meso-mechanically informed incremental non-linear constitutive relation of macroscopic gradient-enhanced Cosserat continuum is derived from volume averages of the RVE-scale solutions. Finally the thermodynamic framework is set up to define meso-mechanically informed anisotropic damage and healing factors, anisotropic net damage factors combining both damage and healing effects, and plastic strains. Densities of damage, plastic and total dissipative energies as well as non-dissipative healing energy, as scalar internal state variables, are provided to compare the effects of damage, healing and plasticity on material failure and structural collapse. The numerical example of strain localization and softening problem is performed to demonstrate the performance and applicability of the proposed multiscale modeling and characterization method of coupled damage-healing-plasticity for granular materials.