An Assessment of the Evolving Microstructural Model of Inelasticity Coupled With Dislocation- and Disclination-Based Incompatibilities

Abstract

The evolving microstructural model of inelasticity (EMMI) previously developed as an improvement over the Bammann–Chiesa–Johnson (BCJ) material model is well known to describe the macroscopic nonlinear behavior of polycrystalline metals subjected to rapid external loads such as those encountered during high-rate events possibly near shock regime. The improved model accounts for deformation mechanisms such as thermally activated dislocation motion, generation, annihilation, and drag. It also accounts for the effects of material texture, recrystallization and grain growth and void nucleation, growth, and coalescence. The material incompatibilities, previously disregard in the aforementioned model, manifest themselves as structural misorientation where ductile failure often initiates are currently being considered. To proceed, the representation of material incompatibility is introduced into the EMMI model by incorporating the distribution of the geometrically necessary defects such as dislocations and disclination. To assess the newly proposed formulation, classical elastic solutions of benchmarks problems including far-field stress applied to the boundary of body containing a defect, e.g., voids, cracks, and dislocations, are used to compute the plastic velocity gradient for various states of the material in terms of assumed values of the internal state variables. The full-field state of the inelastic flow is then computed, and the spatial dependence of the dislocations and disclination density is determined. The predicted results shows good agreement with finding of dislocation theory.