Consistent treatment of ageing-time evolution in McCormick type material models

This work enhances conventional constitutive models for dynamic strain ageing (DSA) based on McCormick’s ageing-time evolution, which incorrectly predicts continuous hardening even within loading stages without plastic flow. An adapted evolution equation is proposed that ties ageing-time progression to the yield surface, ensuring that DSA develops only when dislocations are energetically inclined to glide. To implement such a model consistently, the classical predictor–corrector scheme is revised, and two alternative return-mapping algorithms are established to ensure robust classification of elastic, pseudo-elastic, and plastic states. Numerical examples and experimental data demonstrate that both approaches maintain the predictive capability of the original model while ensuring a consistent and physically meaningful evolution of internal variables.