Strain path dependency in sheet metal. Experiments and models

Sheet metal forming processes are used to create products that have a high stiffness combined with a small weight. To determine the settings of such a production process, fundamental knowledge of the mechanical behaviour of the metal and of the process itself is required. With the introduction of the finite element software a new opportunity for cost reduction was presented. The finite element method allows for optimisation of forming process with a computer, instead of with a costly trial and error process in the workshop. Amongst the various models that are used in this tool, a material model is used to describe the mechanical behaviour of the sheet. The accuracy of the prediction of the finite element software is determined by the accuracy of its components. In this thesis, the influence of the strain path on the mechanical behaviour is investigated. Experiments are used to improve the material models and to improve the overall predictions of the finite element method.