Modeling strain hardening during cyclic thermal shock tests of tungsten

An original model is proposed in order to simulate elastic-plastic transients inside tungsten subjected to cyclic thermal loads expected due to plasma instabilities called “edge-localized modes” in ITER. The model assumes that plasticity is achieved by thermally-activated dislocation motion and it accounts for both isotropic and kinematic hardening. Their relative contributions to the material response are tuned in order to reproduce uniaxial tensile tests performed at different temperatures and different strain rates in various tungsten grades. The model is designed for application as a user-defined material law in fully implicit finite element simulation of thermomechanical loads. The first predictions of the build-up of residual stresses are observed to be qualitatively in line with experimental trends.