Thermo-viscoplastic behavior of AA6061 under dynamic biaxial loadings

In this study, a calibration procedure of a thermo-viscoplastic hardening model of metallic sheets under biaxial stretching loadings is investigated. The proposed method is applied on an aluminium alloy (AA6061) from ambient temperature up to 200°C in the intermediate strain rate range. In a first step, uniaxial tensile tests are performed and show that this alloy exhibits both temperature and strain rate dependent hardening behavior. Based on this experimental database, a thermo-viscoplastic hardening model is calibrated. This model is then introduced in the FE modeling of the in-plane equi-biaxial tensile test. The specimen shape used in this study has been previously defined and validated by the authors for the identification of the viscoplastic hardening models at large strains. Numerical results show the capability of the biaxial tensile test performed on a dedicated flat cross specimen to identify both the temperature and strain rate dependencies of the strain hardening behavior of metallic sheets.