A dislocation-based flow rule with succinct power-law form suitable for crystal plasticity finite element simulations

The physical interpretation of the power-law flow rule from the classic Kocks model suggests that strain rate sensitivity is determined by an empirical parameter that differs from the zero-stress activation energy. This paper proposes a dislocation bow-out model that seeks to further interpret the physical significance of strain rate sensitivity of face-centered cubic (fcc) metals without involving empirical terms. Interestingly, strain rate sensitivity is found to rely on the ratio of the obstacle strength to the zero-stress activation energy. The values of strain rate sensitivity obtained from our calculations match well with the experimental data for pure fcc metals. The resulting flow rule maintains a mathematically concise power-law form with parameters having clear physical meanings and sufficient accuracy. The concise power-law form of the present model enables its easy implementation in the crystal plasticity finite element method and offers flexibility to simulate stress-strain curves of fcc metals deformed at a wide range of temperatures and strain rates.

Automated summary

This study introduces a new dislocation bow-out model to interpret the strain rate sensitivity of fcc metals without using empirical terms. The research results indicate that strain rate sensitivity depends on the ratio of obstacle strength to zero-stress activation energy, and the values obtained match well with experimental data.