SUMMARY

Crystal Plasticity has been used as a higher order model to simulate metal deformation for years and has gained much backing as a credible methodology to introduce the inhomogeneity introduced by individual grains; however, the constitutive relations that define how the structure evolves are based largely on empirical fits to macroscale quantities that lack information from mesoscale deformation. Furthermore, the heterogeneous deformation and evolution of materials measured experimentally is not accurately modeled by current crystal plasticity models with homogeneous material properties. In light of this, a heterogeneous crystal plasticity finite element model was created in order to understand the effect that grains have on the material properties and how they pertain to metal deformation. Because grains are the fundamental length scale at which mesoscale deformation is governed, they serve as the key source of the heterogeneity for deformation at the mesoscale. Also, a new formulation for kinematic hardening was created in order to understand the inability for the microstructure to refine and therefore create further plastic deformation sources. While the kinematic hardening formulation violates the Von-Mises criterion of five independent slip systems, this is a non-issue as experimental observations of deformation patterns reveal that only two to three systems are active at each material point. By limiting the irreversible plastic deformation, a combined isotropic kinematic hardening model can be developed solely in terms of physically observed phenomena. Both of these models are fit to and compared with experimental data on OFHC Cu, and recommendations for future experimental testing to validate microstructural evolution and parameters are made.