On the formulation of the mechanical threshold stress model

The mechanical threshold stress (MTS) model is slightly generalized, improving its applicability to continuum and crystal plasticity frameworks by removing its mathematical singularities. A proper scaling of the activation energy is introduced, ensuring a proper degeneration towards the stress–strain rate power-law behaviour. A minimum of changes are made, preserving the model parameters and predictability under conditions for which it has been tuned and applied to earlier. However, two important additional constraints are added to the parameter optimization of the MTS model. A simple application is mathematically formulated and numerically implemented, namely an elasto-plastic formulation applied to a uniaxial tensile/compression test, taking into account the elasticity of the tools of the tensile machine. Generic model results are calculated for OFE copper strain reversals with strain rate changes.