Development and Application of Micromechanical Material Models for the Characterization of Materials

The concept of the local approach is applied to investigate different damage mechanisms of structural steels by micromechanical material models. Static and dynamic fracture resistance curves for a neutron-embrittled weld material are derived from tensile and Charpy-type specimens with the modified Gurson model. The behaviour of a test piece with a crack in the fenitic base material beneath an austenitic cladding could well be predicted. A constitutive model for creep and creep rupture was developed, implemented in a finite element program and applied to tests on a 12 % Cr steel. The model is a combination of the viscoplastic Robinson model and a damage mechanics model. It is formulated with internal variables for isotropic and kinematic hardening and with a scalar damage parameter. The application of the model to modified C(T) specimens with different hole diameters shows a good agreement between the predictions and the experiments.