A dislocation-based constitutive description for modelling the thermo-viscoplastic behaviour of face-centered cubic metals was developed. The constitutive description, which was founded on the concepts of thermal activation analysis and dislocation dynamics, assumed the plastic flow additively decomposed into internal stress and effective stress. The internal stress represented the applied stress required for the transmission of plastic flow between the polycrystal grains and it was defined by the Hall–Petch relationship. The effective stress formulation, which was the main innovative feature of this work, represented the thermally activated deformation behaviour. This was defined taking into account the interrelationship between strain rate and temperature, and gathers structural evolution dependence. This structural evolution was described as a function of dislocations density, which acts as internal state variable in the material deformation behaviour. A systematic procedure for identification of the material parameters was developed and the model was applied to define the behaviour of annealed OFHC copper. The analytical predictions of the constitutive description were compared with the experimental data reported by Nemat-Nasser and Li (1998). A good correlation between experiments and analytical predictions was found within wide ranges of strain rate and temperature.

A Dislocation-Based Constitutive Description for Modeling the Behavior of FCC Metals Within Wide Ranges of Strain Rate and Temperature. J.A.Rodríguez-Martínez, M.Rodríguez-Millán, A.Rusinek, A.Arias: Mechanics of Materials, 2011, 43[12], 901-12