A constitutive description of the strain rate and temperature effects on the mechanical behavior of materials

The Zerilli and Armstrong (Z–A) model and the mechanical threshold stress (MTS) model have been widely employed to study the strain rate-dependent behavior of materials, but their predictions may sometimes deviate from the experimental results. In this paper, the two well-known models are first reviewed and compared. Their essential relevance is discussed, and the temperature dependences of the parameters in the MTS model are clarified. By using the thermal activation theory, we propose a novel constitutive relation to describe the mechanical behavior of materials in a wide range of strain rate and temperature. Our model combines the advantages of Z–A and MTS models. It can appropriately predict the dependence of the flow stress on the strain rate and temperature, as well as the variation of the activation volume with the thermally activated stress and temperature. We demonstrate the rationality and efficacy of the present model by comparing our theoretical predictions with relevant experimental results in the literature.