1. Viscoplastic behavior

1.1 Norton-Hoff law of viscoplastic behavior

From a physical point of view, plastic flow stress depends on the strain rate when hot, since dislocation displacement is thermally activated, which means that it also depends on temperature (see figure 9 in [42] ).

The simplest generalization of the tensile results is to assume that the plastic flow stress σ ₀ evolves like the tensile stress and depends only on $\stackrel{·}{\overline{\epsilon }}$ ,...