Formability analysis of AA6016-T4 aluminium alloy sheets subjected to roping
Due to its good formability characteristics, AA6xxx aluminium alloys have become popular as a light-weight alternative to steel for components produced by stamping operations for use in the bodywork of cars. In this thesis, a short introduction to aluminium alloys as a material, along with a general presentation to key theory relevant to metal sheet forming was given, including several state-of-the-art anisotropic yield criteria, hardening laws, and instability and fracture criteria. Some of the presented models were calibrated to data from the experimental programme conducted by Dimitry Vysochinskiy in 2012 on AA6016-T4 sheets subjected to the phenomenon of roping. A method to model the effects of roping in aluminium alloy sheets was proposed and implemented in an FEA-model in LS-DYNA. Using the Yld2003 anisotropic yield criterion, and the isotropic two-term Voce hardening law, experimental forming limit were recreated with good accuracy for proportional strain paths using two different local necking instability criteria.