Simulation of microplasticity-induced deformation in uniaxially strained ceramics by 3-D Voronoi polycrystal modeling

A three-dimensional Voronoi polycrystal model for analyzing heterogeneous phenomena and microplasticity in polycrystalline solids has been developed. The crystal modeling employed considers compression-dependent anisotropic elasticity and rate-dependent crystal plasticity. Implemented into the ABAQUS/Standard code, the model is used to investigate the role of microplasticity via 〈1 1 2̄ 0〉{0 0 0 1} basal slip in the response of polycrystalline hexagonal ceramics under uniaxial-strain shock compression. Finite element simulations using a 600-grain polycrystal model and the crystal properties of α-6H silicon carbide are performed and compared with the experimental measurements on the material in its polycrystalline form. The results show that macroscopic flow can evolve through the collective actions of basal-slip-only microplasticity without causing physically unreasonable micromechanical states. The computed volume-averaged response matches the experimental data very well up to a longitudinal stress of ∼20 GPa, including the phenomenon of Hugoniot elastic limit (HEL) and the post-HEL behavior. The results at higher stresses suggest, however, that the stress concentrations due to the evolution of strongly heterogeneous plastic deformation are sufficiently intense to initiate secondary slip systems and/or other microdamages. Issues related to the micromechanisms that may govern the inelastic response of shock-compressed ceramics are discussed in detail.