Isotropic/Kinematic Hardening in Thermoplasticity

Whereas the change of material properties due to change in the temperature can easily be realized, the coupling of the different energy sources is less obvious at a first glance. However, taking advantage of thermodynamics, the different couplings will almost automatically be taken care of. Therefore, when considering thermoplasticity, it is advantageous to make full use of thermodynamics, both when establishing the evolution laws for the material model, the second law of thermodynamics, as well as establishing a proper heat equation, the first law of thermodynamics, which includes the possible heat exchanges. Here focused is on thematerialmodel required for describing cyclic loading, which combines isotropic and kinematic hardening. During cyclic loading and in particular when large plastic strains develop, i.e., dissipation, a large temperature increase can usually be detected, in some cases around hundred of degrees. This requires that a thermodynamically consistent model is developed. For the model description, first a general discussion of the mechanical and thermal response of thermoplasticity models will be considered; this is then followed by a description of a specific model where all necessary couplings are present